Thèses : « Single and Multi-junction Solar Cells »

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Shim, Jae Won. « Study of charge-collecting interlayers for single-junction and tandem organic solar cells ». Diss., Georgia Institute of Technology, 2014. http://hdl.handle.net/1853/51820.

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A hole-collecting interlayer layer for organic solar cells, NiO, processed by atomic layer deposition (ALD) was studied. ALD-NiO film offered a novel alternative to efficient hole-collecting interlayers in conventional single-junction organic solar cells. Next, surface modifications with aliphatic amine group containing polymers for use as electron-collecting interlayers were studied. Physisorption of the polymers was found to lead to large reduction of the work function of conducting materials. This approach provides an efficient way to provide air-stable low-work function electrodes for organic solar cells. Highly efficient inverted organic solar cells were demonstrated by using the polymer surface modified electrodes. Lastly, charge recombination layers of the inverted tandem organic solar cells were studied. Efficient charge recombination layers were realized by using the ALD and the polymer surface modification. The charge recombination layer processed by ALD provided enhanced electrical and barrier properties. Furthermore, the polymer surface modification on the charge recombination layers showed large work function contrast, leading to improved inverted tandem organic solar cells. The inverted tandem organic solar cells with the new charge recombination layer showed fill factor over 70% and power conversion efficiency over 8%.

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Lynch, Marianne Catherine. « Modelling and optimisation of single junction strain balanced quantum well solar cells ». Thesis, Imperial College London, 2011. http://hdl.handle.net/10044/1/8479.

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In an attempt to find the optimum number of wells for maximum conversion efficiency a pair of otherwise identical strain balanced samples, one containing 50 wells and the other 65 wells have been characterised. The 65 well sample is found to possess a lower predicted efficiency than the 50 well sample, suggesting that the optimum well number lies between these values. Devices grown using tertiary butyl arsine (TBAs) are found to possess comparable conversion efficiencies to the control cells grown using arsine and slightly superior dark IV characteristics, indicating that TBAs may be substituted for arsine without loss of device efficiency and may even be beneficial to cell performance. Several fundamental refinements to the existing quantum efficiency model of are explored. Firstly, expressions for the strained band gaps are derived. A value for the conduction band offset is determined using the difference in energy between the heavy and light hole exciton peaks in low temperature photo current scans and found to be 0.55±0.03. The magnitude of the el-hhl exciton binding energy is also estimated from these scans and found to be in excellent agreement with the value obtained from a simple, parameterized expression for the exciton binding energy. Finally, an absolute calculation for the absorption coefficient is incorporated into the quantum efficiency model and values for the heavy and light hole in-planes masses are obtained. The model is found to underestimate the level of absorption in the intrinsic region by an amount consistent with estimates of the magnitude of the reflection from the back surface. The conversion efficiency of a sample predicted using SOL is compared to an independently obtained value. Good agreement is observed between the two results (25.3% and 25.7% for 317 suns AM1.5D). Additionally, an optimum structure for illumination by the AM1.5D spectrum was found to be a 120A well ofIno.lGaAs.

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Mahajumi, Abu Syed. « Type-II gallium antimonide quantum dots in gallium arsenide single junction solar cells ». Thesis, Lancaster University, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.658211.

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The novel idea of GaSb quantum dots (QDs)1 quantum rings (QRs) stacked layers single junction solar cells have been investigated for the examination and enhancement of the infrared photo response. Initially the investigation used photoluminescence to probe the optical properties of a type-II material interface between GaSb/GaAs using optimum growth temperature for QDs/QRs with two different growth modes (Stranski-Krastanow (SK) and exchange growth); and two different GaSb deposition thickness (1.5ML and 2.IML). The photoluminescence spectra of the stacked epilayers confirmed that the dominant radiative recombination mechanism was band-to-band in the GaSb QDs/QRs stacked layers. Excellent structural quality is observed in each sample with no threading dislocations (by Transmission Electron Microscopy (TEM)). The composition of the QRs is close to 100 % GaSb with high purity GaAs centres. The ring density per layer is approximately 1010 rings/cm2 with no significant variation in size or density in the separate layers. II Rapid thermal annealing (RTA) has been used to tailor the optical properties of 10-layer stacks of type-II GaSb self-assembled QDs and QRs embedded within GaAs grown by molecular beam epitaxy. An increase in PL emission intensity and a blue shift in peak energy in both types of QD stacks were observed, along with changes in the activation energy for PL quenching. These effects were attributed to Sb-As intermixing and size effects with corresponding changes in the band structure and an increase in the oscillator strength associated with the transformation towards type-I behaviour. It has been concluded that postgrowth rapid thermal annealing can be used to tune the spectral response and control carrier recombination and escape properties of stacked GaSb QD for more effective use in devices such as solar cells and lasers. The final part of the investigation examined the properties of multi-layer QDs/QRs single junction solar cells (SC) to obtain an understanding of the operation and characteristics of the devices. Three kinds of solar cells were fabricated; one is intrinsic layer with ? layers of QDs/QRs, another comprises 10 layers and the final one is control cells (without QDs/QRs).

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Zhang, Haoquan S. M. Massachusetts Institute of Technology. « An integrated multi-input single-output buck converter for laterally-arrayed multi-bandgap solar cells ». Thesis, Massachusetts Institute of Technology, 2019. https://hdl.handle.net/1721.1/121745.

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Thesis: S.M., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2019
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 151-156).
Concentrated Photovoltaic (CPV) systems provides a potentially low-cost and high-efficiency alternative to conventional mono-crystalline Si panel PV systems, and a new CPV system with Laterally-Arrayed Multi-Bandgap (LAMB) cells is introduced. In this thesis, an IC-based Multi-Input Single-Output (MISO) power converter, which serves as the small-footprint and self-powered power management module of the CPV system, is designed and tested. The proposed converter shall efficiently harvest energy from 4 types of solar cells and track the Maximum Power Point (MPP) at the cell-block level. First, the circuit topology, MPP Tracking (MPPT) algorithm, and control mechanism are verified with discrete converters, then a qualitative demonstration is conducted outdoors to show the concept of the entire CPV system with power management. Finally, a first-generation integrated converter, with the passive components, Analog/Digital converters and a MPPT-enabling micro-controller off-chip, is implemented.
by Haoquan Zhang.
S.M.
S.M. Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science

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Fifer, Tommy L. « Radiation effects on multi-junction solar cells ». Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2001. http://handle.dtic.mil/100.2/ADA401081.

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Thesis (M.S. in Electrical Engineering) Naval Postgraduate School, Dec. 2001.
Thesis advisor(s): Michael, Sherif . "December 2001." Includes bibliographical references (p. 65-67). Also available online.

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Mantilla, Pérez Paola. « Multi-junction thin film solar cells for an optimal light harvesting ». Doctoral thesis, Universitat Politècnica de Catalunya, 2017. http://hdl.handle.net/10803/406044.

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Thin film photovoltaics encompass a group of technologies able to harvest light within a few microns thickness. The reduced thickness allows a low cost of manufacture while making the films flexible and adaptable to different surfaces. This, combined with their low weight, positioned thin film solar cells as ideal candidates for building integrated photovoltaics. For the latter, organic solar cells (OSC) can provide a high quality semi-transparency that closely mimics the aesthetics of standard windows. Indeed, some unique features of organic solar cells make them the optimal solution for applications where standard Si technology cannot be used. However, for large-scale electricity production where efficiency is, perhaps, the most determining factor, newer thin film technologies like perovskites solar cells may be a more adequate option. At the moment of writing this thesis, state of the art efficiencies of single junction perovskites nearly double that of the best single junction organic solar cell. A limitation found in both technologies, especially in organics and to a lesser degree in perovskites, is the low mobility of the carriers. This, together with other processing shortcomings in the organic absorbers and perovskites limit their thickness to 100-130 nm, and 500-600 nm, respectively. In summary, light management must be an essential ingredient when designing device architectures to achieve the optimal performance in the specific application being considered. In this thesis, in order to achieve an optimal light harvesting and therefore increase the performance of thin film solar cells, we take two approaches. On one hand, we increase the total thickness of the absorber material used in the device without increasing the thickness of the single active material layer and, on the other hand, we combine complementary absorbers to cover a wider portion of the solar spectra. These approaches pose the double challenge of finding the optimal electromagnetic field distribution within a complicated multilayer structure containing two or more active layers, while at the same time implementing an effective charge collection or recombination in the intermediate layers connecting two adjacent sub-cells. In the case of OSC, we consider multi-junction cells where the same active material is used in all the junctions. This can be implemented by fabricating structures where the active layer thickness in each sub-cell does not exceed the 100 nm. For other types of thin film solar cells, we consider configurations using complementary absorbers. In both cases, but particularly in the former one, a systematic approach to optimize light absorption is needed. In order to obtain such optimal configurations, we implement an inverse integration approach combined with a transfer matrix calculation of the electric field. Furthermore, we develop several new approaches to optimize charge collection in the sub-cell interconnection layers which we apply to tandem, triple, 4-terminal and series-parallel configurations. The thesis has been organized into five chapters. Chapter 1 introduces concepts required for the development of the thesis work including the optical model. Chapter 2 describes the optical optimization and experimental implementation of current-matched multi-junction devices using PTB7:PC71BM, including applications. In order to profit from the advantage of electrically separated devices, Chapter 3 evaluates different types of 4-terminal architectures using PTB7:PC71BM and PTB7-Th:PC71BM. In one of the architectures we establish a serial-connection between sub-cells while in other we leave the sub-cells completely independent. Chapter 4 theoretically proposes a novel monolithic architecture combining perovskites and CIGS which does not require current-matching. Finally, in Chapter 5, an in-depth study of the semi-transparent inner electrodes is given that include vacuum-based and solution-processed layers.
La fotovoltaica de capa delgada engloba un grupo de tecnologías capaces de capturar la luz en tan sólo unos pocos nanómetros de espesor. Su bajo costo de manufactura, flexibilidad y bajo peso, hace a las capas delgadas candidatas ideales para la integración en edificios. En particular, las celdas orgánicas pueden proveer una transparencia de alta calidad similar a las ventanas convencionales irrealizable con tecnologías basadas en Silicio. Sin embargo, para la producción de electricidad a gran escala en donde la eficiencia es, tal vez, el factor determinante, existen nuevas tecnologías como las celdas solares de perovskita que pueden resultar más adecuadas. Al momento de escribir esta tesis, las eficiencias de celdas de perovskita de simple unión casi duplican la de las mejores celdas orgánicas de simple unión. Una limitante de ambas tecnologías, en especial de las celdas orgánicas y en menor medida de las perovskitas, es la baja movilidad de las cargas. Esta, junto a otras desventajas de los absorbentes orgánicos y perovskitas limita su espesor al rango de los 100 a los 130 nm, y entre los 500 a 600 nm, respectivamente. En resumen, el manejo de la luz debe constituir un ingrediente esencial para el diseño de los dispositivos, tal que se consiga un desempeño óptimo en la aplicación para la cual sean considerados. En esta tesis, con el fin de alcanzar un aprovechamiento óptimo de la luz y por ende aumentar el desempeño de las celdas solares de capa delgada, utilizamos dos enfoques. Por un lado, aumentamos el espesor total de material absorbente dentro del dispositivo sin incrementar el espesor de las capas actives individuales y por otro lado, combinamos absorbentes complementarios para cubrir una porción más amplia del espectro solar. Estos enfoques conllevan al doble reto de encontrar la distribución de campo electromagnético óptima dentro de una estructura compleja de multicapas con dos o más capas activas, junto a la implementación de una recolección o recombinación de cargas efectiva por parte de las capas intermedias encargadas de conectar dos subceldas adyacentes. En el caso de las celdas orgánicas, consideramos celdas de multiunión usando el mismo material activo para todas las subceldas. Para implementarlas, se realizan estructuras cuyas capas activas no excedan los 100 nm. También estudiamos configuraciones donde los materiales tienen absorciones complementarias usando perovskitas. En ambos casos, sobretodo en el primero, se requiere un método sistemático para optimizar el aprovechamiento de la luz. Para obtener las configuraciones óptimas empleamos una estrategia de integración inversa junto con un cálculo del campo eléctrico basado en el modelo de matriz de transferencia. Además, desarrollamos nuevas estrategias para optimizar la colección de cargas en las capas de interconexión de las subceldas aplicables a dispositivos tipo tandem, triple, 4-terminales y serie-paralelo.

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Kolhatkar, Gitanjali. « Characterisation of high-efficiency multi-junction solar cells and tunnel junctions ». Thesis, University of Ottawa (Canada), 2011. http://hdl.handle.net/10393/28939.

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Tunnel junctions for use in solar cells and monolithic multi junction solar cells are studied experimentally. The current density-voltage characteristic of an AlGaAs/AlGaAs tunnel junction having a mesa resistance of 0.11 mO·cm2 is determined using time-averaged measurements. A tunneling peak higher than the operating point of a solar cell is recorded by this method, with a value of ∼950 A/cm2. Due to the unstable nature of the negative differential resistance region of the current density-voltage curve, measurements of the tunneling peak and valley current densities are obscured. A time-dependent analysis is performed on this sample, from which a tunneling peak of a value larger than 1100 A/cm 2 is determined. An A1GaAs/InGaP tunnel junction having a tunneling peak of 80 A/cm2 is presented. Multi junction solar cells fabricated using indium tin-oxide as transparent top electrodes are measured. These cells have a maximal efficiency of 25.1% at 3 suns illumination and 26.1% at 20 suns, ∼40% lower efficiency than the standard multi junction solar cell.

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Walker, Alexandre W. « Bandgap Engineering of Multi-Junction Solar Cells for Enhanced Performance Under Concentration ». Thèse, Université d'Ottawa / University of Ottawa, 2013. http://hdl.handle.net/10393/26240.

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This doctorate thesis focuses on investigating the parameter space involved in numerically modeling the bandgap engineering of a GaInP/InGaAs/Ge lattice matched multi-junction solar cell (MJSC) using InAs/InGaAs quantum dots (QDs) in the middle sub-cell. The simulation environment – TCAD Sentaurus – solves the semiconductor equations using finite element and finite difference methods throughout well-defined meshes in the device to simulate the optoelectronic behavior first for single junction solar cells and subsequently for MJSCs with and without quantum dots under concentrated illumination of up to 1000 suns’ equivalent intensity. The MJSC device models include appropriate quantum tunneling effects arising in the tunnel junctions which serve as transparent sub-cell interconnects. These tunneling models are calibrated to measurements of AlGaAs/GaAs and AlGaAs/AlGaAs tunnel junctions reaching tunneling peak current densities above 1000 A/cm^2. Self-assembled InAs/GaAs quantum dots (QDs) are treated as an effective medium through a description of appropriate generation and recombination processes. The former includes analytical expressions for the absorption coefficient that amalgamates the contributions from the quantum dot, the InAs wetting layer (WL) and the bulk states. The latter includes radiative and non-radiative lifetimes with carrier capture and escape considerations from the confinement potentials of the QDs. The simulated external quantum efficiency was calibrated to a commercial device from Cyrium Technologies Inc., and required 130 layers of the QD effective medium to match the contribution from the QD ground state. The current – voltage simulations under standard testing conditions (1 kW/cm^2, T=298 K) demonstrated an efficiency of 29.1%, an absolute drop of 1.5% over a control structure. Although a 5% relative increase in photocurrent was observed, a 5% relative drop in open circuit voltage and an absolute drop of 3.4% in fill factor resulted from integrating lower bandgap nanostructures with shorter minority carrier lifetimes. However, these results are considered a worst case scenario since maximum capture and minimum escape rates are assumed for the effective medium model. Decreasing the band offsets demonstrated an absolute boost in efficiency of 0.5% over a control structure, thus outlining the potential benefits of using nanostructures in bandgap engineering MJSCs.

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Judkins, Zachara Steele. « A market analysis for high efficiency multi-junction solar cells grown on SiGe ». Thesis, Massachusetts Institute of Technology, 2007. http://hdl.handle.net/1721.1/42143.

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Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2007.
Includes bibliographical references (leaves 50-53).
Applications, markets and a cost model are presented for III-V multi-junction solar cells built on compositionally graded SiGe buffer layers currently being developed by professors Steven Ringell of Ohio State University and Eugene Fitzgerald of MIT. Potential markets are similar to those currently occupied by high efficiency multi-junction space solar cells grown on a Germanium substrate. Initial cost analysis shows that at production volumes similar to those of the state of the art, cost could be reduced by a factor of' four. Significant market share may be gained in both the space and terrestrial PV markets due to improved performance associated with superior materials properties advantages as well as production cost reductions.
by Zachary Steele Judkins.
M.Eng.

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Korostyshevsky, Aaron. « Characterization of Radiation Damage in Multi-Junction Solar Cells Using Light-Biased Current Measurements ». Connect to full text in OhioLINK ETD Center, 2008. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=toledo1224614484.

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Thesis (M.S.)--University of Toledo, 2008.
Typescript. "Submitted as partial fulfillments of the requirements for the Master of Science Degree in Physics." "A thesis entitled"--at head of title. Bibliography: leaves 41-42.

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Lee, Kan-Hua. « Photon coupling effects and advanced characterisations of multiple-quantum-well multi-junction solar cells ». Thesis, Imperial College London, 2014. http://hdl.handle.net/10044/1/24747.

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Achieving optimal band-gap combinations of multi-junction solar cells at production level is the most difficult challenge in concentrator photovoltaics. To improve the state-of-the-art InGaP/InGaAs/Ge triple-junction cells, it requires that the band gaps of the top and middle junction to be lower or an additional 1 eV junction. This involves lattice-mismatch growth or introducing dilute nitrides materials, which makes it difficult to scale up to production at low cost. Strain-balanced multiple quantum wells (MQWs) in the middle junction has been very well-studied as a means to adjust the absorption edges of the middle junction in multi-junction solar cells. To fully optimise the efficiency of solar cells with MQW GaAs subcell, an InGaP top cell with MQWs also has to be introduced to achieve current-matching. The aim of this thesis is to address the issues of production multi-junction cell with MQWs. We studied the material properties of MQW InGaP subcells and demonstrated its strong photon coupling effects in multi-junction devices. Several characterisation techniques were developed to acquire deeper understanding of the material qualities and sheet resistance of MQW solar cells.

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Tournet, Julie. « III-Sb-based solar cells and their integration on Si ». Thesis, Montpellier, 2019. http://www.theses.fr/2019MONTS003/document.

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Les matériaux III-Sb ont prouvé leur potentiel pour la réalisation de composants opto-électroniques dans des domaines aussi variés que les télécommunications ou l'environnement. Cependant, ils restent une filière quasi-inexplorée pour les systèmes photovoltaïques classiques. Dans ce projet de recherche, nous voulons démontrer que les composants à base d'antimoniures sont des candidats prometteurs pour des cellules solaires à haute efficacité et bas coût. Leurs avantages sont multiples : non seulement offrent-ils un large panel d'alliages accordés en maille et des jonctions tunnel à basse résistivité, mais ils permettent aussi une croissance directe sur substrat de Si. Nous étudions donc les briques élémentaires d'une cellule solaire multi-jonction intégrée sur Si. Tout d'abord, nous développons la croissance et fabrication de cellules homo-épitaxiales en GaSb. Les caractéristiques tension-intensité (J-V) mesurées sont proches de l'état de l'art avec une efficacité sous un soleil de 5.9 %. Puis, nous intégrons une cellule à simple jonction GaSb sur un substrat de Si par épitaxie par jet moléculaire (EJM). Les analyses de diffraction X (DRX) et de microscopie à force atomique (AFM) montrent des propriétés de structure et morphologie proches de celles reportées pour des buffers métamorphiques similaires dans la littérature. Nous adaptons alors la configuration de la cellule pour éviter la haute densité de défauts à l'interface GaSb/Si. La cellule hétéro-épitaxiale a une efficacité réduite de 0.6 %. Ce résultat est néanmoins proche des dernières avancées sur les cellules GaSb sur GaAs, et ce, malgré un désaccord de maille plus important. Enfin, nous étudions l'épitaxie d'AlInAsSb. Cet alliage pourrait en théorie atteindre une grande gamme d'énergies de bande interdite tout en restant accordé sur GaSb. Néanmoins, il souffre d'une lacune de miscibilité importante, le rendant sujet à la ségrégation de phase. Il n'y a que peu de mentions de l'AlInAsSb dans la littérature, et toutes rapportent des conditions de croissance instables et des énergies de bande interdite plus basses qu'attendues. Nous réussissons à produire des couches de bonne qualité d'AlInAsSb dont la composition en Al varie de 0.25 à 0.75 et ne présentant aucun signe macroscopique de décomposition de phase. Toutefois, l'observation au microscope à transmission électronique (TEM) révèle des fluctuations de composition nanométriques. Les données de photoluminescence (PL) sont étudiées pour déterminer les propriétés électroniques de l'alliage. Les mesures d'efficacité quantique (QE) montrent que la sous-cellule du haut limite la performance de la cellule tandem. Des modélisations numériques des courbes J-V et QE sont utilisées pour identifier des pistes d'amélioration pour chaque brique élémentaire
III-Sb materials have demonstrated their potential for multiple opto-electronic devices, with applications stretching from communications to environment. However, they remain an almost unexplored segment for classical photovoltaic systems. In this research, we intend to demonstrate that III-Sb-based devices are promising candidates for high-efficiency, low-cost solar cells. Their benefits are two-fold: not only do they offer a wide range of lattice-matched alloys and low-resistivity tunnel junctions, but they also enable direct growth on Si substrates. We thus investigate the building blocks of a GaSb-based multi-junction solar cell integrated onto Si. First, we develop the photovoltaic growth and processing by fabricating homo-epitaxial GaSb cells. Intensity-voltage (J-V) measurements approach the state of the art with 1-sun efficiency of 5.9%. Then, we integrate a GaSb single-junction cell on a Si substrate by molecular beam epitaxy (MBE). X-ray diffraction (XRD) and atomic force microscopy (AFM) analysis show structural and morphological properties close to the best reported in the literature for similar metamorphic buffers. We further adapt the cell configuration to circumvent the high defect density at the GaSb/Si interface. The heteroepitaxial cell results in a reduced efficiency of 0.6%. Nevertheless, this performance is close the most recent advancements on GaSb heteroepitaxial cells on GaAs, despite a much larger mismatch. Last, we investigate the epitaxy of AlInAsSb. This alloy could in theory reach the widest range of bandgap energies while being lattice-matched to GaSb. However, it presents a large miscibility gap, making it vulnerable to phase segregation. AlInAsSb only counts few experimental reports in the literature, all referring to unoptimized growth conditions and abnormally low bandgap energies. We successfully grow good-quality layers with Al composition x_{Al} ranging from 0.25 to 0.75, showing no macroscopic sign of decomposition. Yet, transmission electron microscopy (TEM) observations point to nanometric fluctuations of the quaternary composition. Photoluminescence (PL) data is studied to determine the alloy's electronic properties. We eventually propose and fabricate a tandem cell structure, resulting in 5.2% efficiency. Quantum Efficiency (QE) measurements reveal that the top subcell is limiting the tandem performance. Numerical fits to both J-V and QE data indicate improvement paths for each building block

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Fernández, Jara [Verfasser]. « Development of Crystalline Germanium for Thermophotovoltaics and High-Efficiency Multi-Junction Solar Cells / Jara Fernández ». Konstanz : Bibliothek der Universität Konstanz, 2010. http://d-nb.info/1026012740/34.

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Wilkins, Matthew M. « Design of Multi-junction Solar Cells on Silicon Substrates Using a Porous Silicon Compliant Membrane ». Thèse, Université d'Ottawa / University of Ottawa, 2013. http://hdl.handle.net/10393/24096.

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A novel approach to the design of multi-junction solar cells on silicon substrates for 1-sun applications is described. Models for device simulation including porous silicon layers are presented. A silicon bottom subcell is formed by diffusion of dopants into a silicon wafer. The top of the wafer is porosified to create a compliant layer, and a III-V buffer layer is then grown epitaxially, followed by middle and top subcells. Due to the resistivity of the porous material, these designs are best suited to high efficiency 1-sun applications. Numerical simulations of a multi-junction solar cell incorporating a porous silicon compliant membrane indicate an efficiency of 30.7% under AM1.5G, 1-sun for low threading dislocation densities (TDD), decreasing to 23.7% for a TDD of 10^7 cm^-2.

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Wilkins, Matthew. « Multi-Junction Solar Cells and Photovoltaic Power Converters : High-Efficiency Designs and Effects of Luminescent Coupling ». Thesis, Université d'Ottawa / University of Ottawa, 2017. http://hdl.handle.net/10393/36181.

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Multi-junction photovoltaic devices based on III-V semiconductors have applications in space power systems and terrestrial concentrating photovoltaics, as well as in power-over-fibre and optical power conversion systems. These devices have between two and twenty junctions arranged in tandem, connected in series with optically transparent tunnel diodes. In some cases, they may include as many as eight different materials, including ternary and quaternary alloys, and >100 epitaxial layers in total. A general method for simulating performance of these devices using drift-diffusion based device simulation tools is reviewed. This includes discussion of the geometry, discretization, and physical equations to be solved. A set of material parameters for some important materials is listed, and solutions are shown for an example of a lattice-matched four-junction GaInP / (In)AlGaAs / InGaAsN(Sb) / Ge solar cell including a dilute nitride based p-i-n junction with ∼ 0.9 eV band gap. A sample of this dilute nitride junction with a 650 nm absorber layer was grown by molecular beam epitaxy and was shown to have short-circuit current density of 15.1 mA/cm2, sufficient for use in the 4-junction structure, while transmitting sufficient light through to the bottom (germanium) junction. Open-circuit voltage was up to 0.186 V at 1-sun, increasing to 0.436 V under 1500 suns concentration. The device simulation methodology was extended to include effects of luminescent coupling and photon recycling. These effects are included by adding a term to the electron and hole continuity equations, and the resulting coupled system of equations is solved. No external iterative loop is required, as has been the case in other efforts to model these effects. A five-junction photonic power converter (PPC) is simulated and it is shown that the quantum efficiency of the device is significantly broadened through luminescent coupling. There is a 350 mV reduction in simulated open-circuit voltage (70 mV per junction) if luminescent coupling is neglected. This work was later extended to a 12-junction PPC device, where the simulation predicts a wavelength sensitivity of -1.1%/nm in the absence of luminescent coupling; this is reduced to -0.4%/nm when luminescent coupling is included in the calculation. The latter result, and the overall shape of the simulated quantum efficiency curve agree closely with experimental measurements. Finally, two specific applications of PPCs are demonstrated. The first is in a step-up DC-to-DC converter, where a linear regulator combined with a laser/PPC pair can convert a 3.3 V input (commonly available from a single lithium polymer battery cell) into 12 V. Unlike conventional switching boost converters, this ‘photonic boost converter’ is not a source of ripple. In testing, a >80 dB reduction in ripple was measured compared with an equivalent switching boost converter, limited only by input noise of the instrument.The second application is in a 60 kW, 650 V switching circuit such as might be found in a hybrid or electric vehicle drivetrain. These circuits need several isolated power supplies to power gate drivers for the IGBT or SiC MOSFET switching components. This isolation is commonly provided by a small transformer, which inherently has a parasitic capacitance between primary and secondary windings and creates a path for EMI currents to flow from the high-power components to the power supply and control circuitry. By using a laser/PPC pair to provide the needed isolation, this parasitic capacitance can be largely eliminated; a 20 dB reduction in EMI current reaching the control FPGA is demonstrated.

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Yandt, Mark. « Characterization Techniques and Optimization Principles for Multi-Junction Solar Cells and Maximum Long Term Performance of CPV Systems ». Thesis, Université d'Ottawa / University of Ottawa, 2017. http://hdl.handle.net/10393/35870.

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Two related bodies of work are presented, both of which aim to further the rapid development of next generation concentrating photovoltaic systems using high efficiency multi junction solar cells. They are complementary since the characterization of commercial devices and the systematic application of design principles for future designs must progress in parallel in order to accelerate iterative improvements. First addressed, is the field characterization of state of the art concentrating photovoltaic systems. Performance modeling and root cause analysis of deviations from the modeling results are critical for bringing reliable high value products to the market. Two complementary tools are presented that facilitate acceleration of the development cycle. The “Dynamic real-time I V Curve Measurement System…” provides a live picture of the current-voltage characteristics of a CPV module. This provides the user with an intuitive understanding of how module performance responds under perturbation. The “Shutter technique for noninvasive individual cell characterization in sealed concentrating photovoltaic modules,” allows the user to probe individual cell characteristics within a sealed module. This facilitates non-invasive characterization of modules that are in situ. Together, these tools were used to diagnose the wide spread failure of epoxy connections between the carrier and the emitter of bypass diodes installed in sealed commercial modules. Next, the optimization principals that are used to choose energy yield maximizing bandgap combinations for multi-junction solar cells are investigated. It is well understood that, due to differences in the solar resource in different geographical locations, this is fundamentally a local optimization problem. However, until now, a robust methodology for determining the influences of geography and atmospheric content on the ideal design point has not been developed. This analysis is presented and the influence of changing environment on the representative spectra that are used to optimize bandgap combinations is demonstrated. Calculations are confirmed with ground measurements in Ottawa, Canada and the global trends are refined for this particular location. Further, as cell designers begin to take advantage of more flexible manufacturing processes, it is critical to know if and how optimization criteria must change for solar cells with more junctions. This analysis is expanded to account for the differences between cells with up to 8 subcell bandgaps. A number of software tools were also developed for the Sunlab during this work. A multi-junction solar cell model calibration tool was developed to determine the parameters that describe each subcell. The tool fits a two diode model to temperature dependent measurements of each subcell and provides the fitting parameters so that the performance of multi-junction solar cells composed of those subcells can be modeled for real world conditions before they are put on-sun. A multi-junction bandgap optimization tool was developed to more quickly and robustly determine the ideal bandgap combinations for a set of input spectra. The optimization process outputs the current results during iteration so that they may be visualized. Finally, software tools that compute annual energy yield for input multi-junction cell parameters were developed. Both a brute force tool that computes energy harvested at each time step, and an accelerated tool that first bins time steps into discrete bins were developed. These tools will continue to be used by members of the Sunlab.

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VanDyke, Jamie E. « Modeling laser effects on multi-junction solar cells using Silvaco ATLAS software for spacecraft power beaming applications ». Thesis, Monterey, California : Naval Postgraduate School, 2010. http://edocs.nps.edu/npspubs/scholarly/theses/2010/Jun/10Jun%5FVanDyke.pdf.

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Thesis (M.S. in Space Systems Operations)--Naval Postgraduate School, June 2010.
Thesis Advisor(s): Michael, Sherif ; Second Reader: Scott, Alan. "June 2010." Description based on title screen as viewed on July 14, 2010. Author(s) subject terms: Solar Cell, Photovoltaic, Directed Energy, Power Beaming, Wireless Power Transfer, Multi-junction, Laser, Silvaco, Modeling, Simulation. Includes bibliographical references (p. 115-117). Also available in print.

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Browne, Benjamin. « An experimental and theoretical study of multi-junction and deep-well GaAsP/InGaAs quantum well solar cells ». Thesis, Imperial College London, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.530465.

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Chow, Simon Ka Ming. « Integration of High Efficiency Solar Cells on Carriers for Concentrating System Applications ». Thèse, Université d'Ottawa / University of Ottawa, 2011. http://hdl.handle.net/10393/19932.

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High efficiency multi-junction (MJ) solar cells were packaged onto receiver systems. The efficiency change of concentrator cells under continuous high intensity illumination was done. Also, assessment of the receiver design on the overall performance of a Fresnel-type concentration system was investigated. We present on receiver designs including simulation results of their three-dimensional thermal operation and experimental results of tested packaged receivers to understand their efficiency in real world operation. Thermal measurements from solar simulators were obtained and used to calibrate the model in simulations. The best tested efficiency of 36.5% is obtained on a sample A receiver under 260 suns concentration by the XT-30 solar simulator and the corresponding cell operating temperature is ~30.5°C. The optimum copper thickness of a 5 cm by 5 cm simulated alumina receiver design was determined to be 6 mm and the corresponding cell temperature under 1000 suns concentration is ~36°C during operation.

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Jadhav, Priyadarshani. « Singlet exciton fission, a multi-exciton generation process, in organic semiconductor solar cells ». Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/75635.

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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2012.
Cataloged from PDF version of thesis.
Includes bibliographical references (p. 107-115).
Organic semiconductor photovoltaics hold the promise of cheap production and low manufacturing setup costs. The highest efficiency seen in research labs, ~10% today, is still too low for production. In this work we explore implementations of a multiple exciton generation process, singlet exciton fission, to work around the Shockley-Queisser limit, according to which, all single junctions cells have a theoretical efficiency limit of 33.7%. This is the first implementation of a singlet fission photovoltaic. We measured a singlet fission efficiency of 72% at room temperature. We showed that singlet fission can be implemented in bulk heterojunction photovoltaics, which is an important result since some of the highest efficiency organic photovoltaics in the last 5 years have been bulk heterojunction structures. Secondly, we showed that the magnetic field effect can be used as a probe to investigate triplet dissociation in singlet fission devices. Thirdly, we implemented singlet fission photovoltaics, using the singlet fission material pentacene as donor and low bandgap infrared-absorptive lead chalcogenide quantum dots as acceptors. Singlet fission can enhance the efficiency of organic photovoltaics only if the fission material is paired with an absorptive low-energy-gap material. We find that pentacene triplet excitons dissociate at the pentacene/quantum dot heterojunctions with an internal quantum efficiency of 35%. Lastly, we investigate a series of materials to find a better acceptor in singlet fission photovoltaics using the methods and some results from the previous two investigations. We investigate device structures that pair pentacene and 6,13 diphenyl-pentacene as singlet fission donors with C60 , perylene diimides, PbS quantum dots and PbSe quantum dots as acceptors.
by Priyadarshani Jadhav.
Ph.D.

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Andre, Carrie L. « III-V semiconductors on SiGe substrates for multi-junction photovoltaics ». The Ohio State University, 2004. http://rave.ohiolink.edu/etdc/view?acc_num=osu1100290985.

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Guo, Fei [Verfasser], et Christoph [Akademischer Betreuer] Brabec. « Material and Process Engineering of Printed Semitransparent Organic Solar Cells and Advanced Multi-junction Architectures / Fei Guo. Gutachter : Christoph Brabec ». Erlangen : Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 2015. http://d-nb.info/107736296X/34.

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Veinberg, vidal Elias. « Fabrication, caractérisation et simulation de cellules solaires multi-junction III-V sur silicium ». Thesis, Université Grenoble Alpes (ComUE), 2018. http://www.theses.fr/2018GREAT091/document.

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Des rendements record à plus de 26% ont récemment été démontrés avec des cellules solaires en Si, approchant la limite théorique de 30% pour une seule jonction. Les cellules solaires à multi-jonctions (MJSC) fabriquées à base de matériaux III-V peuvent dépasser cette limite: des rendements supérieurs à 45% ont été reportés pour une cellule à 5 jonctions sous un soleil et pour une cellule à 4 jonctions sous lumière concentrée. Cependant, pour des applications terrestres, le coût élevé de ces technologies impose l’utilisation d’une haute concentration, ce qui augmente la complexité du système.Une solution intermédiaire consiste à fabriquer des cellules solaires III-V à haut rendement sur des substrats Si, moins coûteux que les substrats III-V ou Ge utilisés dans les MJSC classiques. Des rendements supérieurs à 33% ont déjà été démontrés pour des MJSC fabriquées par collage direct. Ceci, combiné aux progrès récents dans la réutilisation des substrats III-V, présage un avenir prometteur pour les cellules solaires tandem III-V sur Si, ce qui pourrait mener à la prochaine génération de systèmes photovoltaïques à haut rendement et faible coût.Dans ce travail de thèse, des cellules solaires tandem AlGaAs//Si à 2 jonctions (2J) et GaInP/AlGaAs//Si à 3 jonctions (3J) ont été fabriquées par collage direct, ce qui a donné lieu à une configuration à 2 terminaux (2T).Différentes techniques de collage ont été étudiées, notamment une approche innovante présentant un potentiel d'industrialisation prometteur pour l’intégration des matériaux III-V sur Si. Les propriétés électriques de l'interface de collage GaAs//Si ont été analysées à l'aide de dispositifs de test dédiés conçus au CEA, permettant d'évaluer la résistance d'interface et le mécanisme de conduction.Des caractérisations et simulations expérimentales ont été effectuées afin d'optimiser le design et le processus de fabrication, conduisant à des rendements record. Pour la sous-cellule supérieure en AlGaAs de la 2J, cela comprend l'utilisation d'une fenêtre en AlInP avec un émetteur en GaInP, formant une hétérojonction n-GaInP/p-AlGaAs, qui améliore les performances pour les faibles longueurs d'onde. De plus, la réduction de l'épaisseur de la couche de collage en GaAs et l'utilisation d'une jonction tunnel en AlGaAs, avec bande interdite plus large, augmentent la transparence et donc le photocourant de la sous-cellule inférieure.Pour la sous-cellule inférieure en Si, les simulations ont permis d'identifier les facteurs clés qui limitent les performances, la durée de vie étant la caractéristique la plus critique dans les cellules Si épaisses utilisées. Dans le cas des interfaces III-V//Si, un émetteur fortement dopé est essentiel pour minimiser la recombinaison de surface et donc augmenter la tension en circuit ouvert. La passivation de la surface arrière est également importante, notamment pour augmenter la réponse dans l’infrarouge. Différents processus de diffusion et d'implantation ont été étudiés pour former l'émetteur. Les processus d'implantation ont montré moins de dégradation de la durée de vie et des surfaces moins rugueux, permettant ainsi le collage sans planarisation chimico-mécanique et donc des niveaux de dopage plus élevés en surface.Finalement, afin d’évaluer correctement le rendement de conversion de ces cellules tandem III-V sur Si, une méthode de caractérisation courant-tension rapide et peu coûteuse, adaptée aux MJSC sous faible concentration a été développée. Cette méthode ne nécessite pas de cellules isotypes parfaitement identiques, à la place, des cellules Si à simple jonction avec filtres optiques sont utilisées. Une efficacité de 23,7% sous 10 soleils a été démontrée de cette manière pour la cellule AlGaAs//Si, qui est le rendement le plus élevé signalé à ce jour pour une cellule tandem à base de Si avec 2J et 2T
Si solar cells with record efficiencies over 26% have been recently demonstrated, approaching the Si single-junction limit of 30%. Multi-junction solar cells (MJSC) based on III-V materials can overcome this limit: efficiencies over 45% have been reported for a 5-junction under 1 sun and for a 4-junction under a concentrated illumination of 300 suns. Due to their elevated cost, these cells could be used in terrestrial applications only if operated under very high sunlight concentration for commercial terrestrial applications, which in turn increases the module and system complexity.An intermediate solution consists in fabricating high efficiency III-V solar cells on Si substrates, which are less expensive than the III-V or Ge substrates used in conventional MJSC. Mechanical-stacked and wafer-bonded solar cells, which avoid the unresolved issues of III-V on Si epitaxy, have already demonstrated efficiencies over 33%. This, combined with the recent advancements in the field of substrate reuse, predict a promising future for III-V on Si tandem solar cells, which could lead the next generation of high-efficiency and low-cost photovoltaics.In this PhD work, 2-junction (2J) AlGaAs//Si and 3-junction (3J) GaInP/AlGaAs//Si tandem solar cells were fabricated. The Si bottom subcell and the III-V top subcell(s) were joined together by wafer bonding, resulting in a 2-terminal (2T) III-V//Si solar cell configuration.Different wafer bonding techniques were studied, including an innovative bonding approach showing promising industrialization potential and thus, opening a new path for III-V on Si processing. The GaAs//Si bonding interface electrical properties were analyzed using dedicated test devices originally conceived at CEA, allowing to evaluate the interface resistance and the conduction mechanism.Experimental characterizations and simulations were performed in order to optimize the design and fabrication process, leading to record efficiencies. For the AlGaAs top subcell of the 2J, this includes the use of an AlInP window together with a GaInP emitter, forming an n-GaInP/p-AlGaAs heterojunction, which improved the short wavelength performance. In addition, the reduction of the GaAs bonding layer thickness and the use of a higher bandgap AlGaAs tunnel junction resulted in a higher transparency and a bottom subcell photocurrent improvement.For the Si bottom subcell, simulations allowed to identify the key factors that limit the performance, being the bulk lifetime the most critical characteristic in the thick Si cells used. In the case of III-V//Si interfaces, a highly doped emitter is crucial to minimize the surface recombination and maximize the open-circuit voltage, outweighing the drop in short-circuit current due to lifetime degradation. Back surface passivation is also important, specially to increase the infrared response. Different diffusion and implantation processes for the emitter formation were studied. Implantation processes showed less bulk lifetime degradation and smoother surfaces, thereby allowing bonding without chemical-mechanical planarization and thus higher doping levels at the surface.Finally, in order to correctly assess the efficiency of these III-V on Si tandem cells, a fast and low-cost current-voltage characterization method adapted for MJSC under low concentration was developed. This method does not require perfectly matched component cells and instead, Si single-junction cells with optical filters are used as pseudo-isotypes. An efficiency of 23.7% under 10 suns was demonstrated this way for the AlGaAs//Si cell, which is the highest efficiency reported to date for a 2J 2T Si-based tandem cell

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Dickerson, Jeramy Ray. « Heterostructure polarization charge engineering for improved and novel III-V semiconductor devices ». Diss., Georgia Institute of Technology, 2014. http://hdl.handle.net/1853/51793.

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Innovative electronic device concepts that use polarization charges to provide improved performance were validated. The strength of the electric fields created by polarization charges (PCs) was suggested to act as an additional design parameter in the creation of devices using III-nitride and other highly polar materials. Results indicated that polarization induced electric fields can replace conventional doping schemes to create the charge separation region of solar cells and would allow for a decoupling of device performance from doping requirements. Additionally, a model for calculating current through polarization induced tunnel diodes was proposed. The model was found to agree well with experimental current values. Several polarization induced tunnel junction (PTJ) designs were analyzed. A novel double-barrier PTJ was conceived that would allow for the creation of a multi-junction solar cell using strained InGaN absorption layers. Future research would include the fabrication of these devices and the inclusion of thermal effects in the model for calculating current through PTJs.

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Liebhaber, Martin Lutz [Verfasser]. « Silicon heterojunction solar cells : From conventional concepts to a singlet fission multi-exciton generating hybrid approach / Martin Lutz Liebhaber ». Berlin : Freie Universität Berlin, 2017. http://d-nb.info/1129174549/34.

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Chenche, Luz Elena Peñaranda. « Avaliação dos métodos de modelagem e parametrização de dispositivos fotovoltaicos mono e multi junção ». Universidade Federal de Uberlândia, 2015. https://repositorio.ufu.br/handle/123456789/14984.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
This work deals with the analysis applied to the main methodologies found in literature for estimating the properties related to the physical phenomena in photovoltaic devices (parametrization), as well as the most important mathematical models used in the calculation of operating electrical characteristics of these devices (characterization). These devices are related to the mono and multi-junction technologies, when they are exposed to a condition where the temperature and solar radiation vary. Therefore, four parametrization methods were shown, including three analytical, and five models of electrical characterization, where two of them are specifically for multi-junction devices. Thus, several case studies were proposed which defined different situations for comparing the performance of the methods evaluated. In this way, the procedures that best fit to each type of photovoltaic technology were identified. Finally, according to the results obtained in the parameterization, the method based on the Generalized Reduced Gradient (GRG) nonlinear algorithm showed greater accuracy for all case studies and for all photovoltaic devices. As for the characterization, the main advantages and disadvantages of all models were determined, highlighting Domínguez, et al. (2010) model, due to the highest robustness and wide application range.
Esta dissertação apresenta uma análise aplicada às principais metodologias encontradas na literatura que permitem determinar as propriedades físicas relativas aos fenômenos que ocorrem nos dispositivos fotovoltaicos (etapa de parametrização), assim como dos modelos matemáticos de maior importância utilizados no cálculo das características elétricas operacionais destes dispositivos (etapa de caraterização). Tais dispositivos referem-se às tecnologias mono e multi junção quando submetidos à variações de temperatura e radiação solar. Portanto, foram apresentados quatro métodos de parametrização, entre eles três analíticos e cinco modelos de caracterização elétrica, sendo dois especificamente para dispositivos multi junção. Assim, estabeleceram-se vários estudos de caso para os quais foram definidas diferentes situações que permitiram comparar o desempenho de cada um dos métodos avaliados. Em consequência, foram identificados os procedimentos que melhor se ajustaram a cada tipo de tecnologia fotovoltaica. Dessa forma, de acordo com os resultados obtidos na parametrização, a metodologia baseada na aplicação do algoritmo de Gradiente Reduzido Generalizado (GRG) não linear, demonstrou maior exatidão para todos os estudos de caso e para todos os dispositivos fotovoltaicos. Já para a caraterização, foram determinadas as principais vantagens e desvantagens entre os modelos aplicados, destacando o modelo de Domínguez, et al. (2010), que apresentou maior robustez e ampla faixa de aplicação.
Mestre em Engenharia Mecânica

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Louarn, Kévin. « Etude et réalisation de jonctions tunnel à base d'hétérostructures à semi-conducteurs III-V pour les cellules solaires multi-jonction à très haut rendement ». Thesis, Toulouse 3, 2018. http://www.theses.fr/2018TOU30002/document.

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L'architecture des cellules solaires multi-jonction permet d'obtenir des records de rendement de conversion photovoltaïque, pouvant aller jusqu'à 46%. Leurs sous-cellules sont chacune conçues pour absorber une partie bien définie et complémentaire du spectre solaire, et sont connectées en série par des jonctions tunnel. La fabrication de cellules solaires tandem InGaP/GaAs d'énergies de bande interdite (" band gap ") 1,87 eV/1,42 eV accordées en maille sur substrat GaAs est bien maîtrisée, et de très hauts rendements peuvent être obtenus en ajoutant une ou deux sous-cellules de plus petit " gap " (1 eV et 0,7eV). Pour cela, les matériaux " petits gaps " fabriqués par Epitaxie par Jets Moléculaires (EJM) doivent être développés ainsi que des jonctions tunnel présentant une faible résistivité électrique, une haute transparence optique et de bonnes propriétés structurales. La croissance EJM et la modélisation de jonctions tunnel GaAs nous a permis d'identifier le mécanisme d'effet tunnel interbande plutôt que le mécanisme d'effet tunnel assisté par les défauts comme mécanisme dominant du transport dans ces structures. Nous avons exploité l'hétérostructure de type II fondée sur le système GaAsSb/InGaAs pour favoriser ce mécanisme d'effet tunnel interbande, et donc obtenir des jonctions tunnel de très faible résistivité tout en limitant la dégradation des propriétés optiques et structurales des composants inhérente à l'utilisation de matériaux " petits gaps " et désaccordés en maille GaAsSb et InGaAs. De plus, nous avons conçu une structure innovante d'hétérojonction tunnel de type II AlGaInAs/AlGaAsSb sous la forme de tampon graduel pour l'incorporation d'une sous-cellule métamorphique à 1 eV. Plusieurs candidats pour le matériau absorbeur à 1 eV à base de nitrure dilué InGaAsN(Bi) ont alors été développés et caractérisés, le contrôle de l'accord de maille étant assuré par un suivi en temps réel de la courbure de l'échantillon pendant la croissance EJM. Des premières cellules solaires III-V à base de GaAs, de nitrure dilué à 1 eV et de GaInAs métamorphique ont été fabriquées afin de valider les architectures développées de jonctions tunnel. Ce travail a permis de démontrer le potentiel de l'hétérostructure de type II GaAsSb/InGaAs pour répondre aux principaux défis de conception et de fabrication des cellules solaires multi-jonction sur substrat GaAs, que ce soit au niveau de la jonction tunnel ou au niveau de l'incorporation des sous-cellules de gap 1 eV
Multi-Jonction Solar Cells (MJSCs) are leading the way of high efficiency photovoltaic devices, with conversion efficiency up to 46%. Their subcells are designed to absorb in a specific and complementary range of the solar spectrum, and are connected in series with tunnel junctions. The tandem architecture InGaP/GaAs - with bandgaps of 1.87 eV and 1.42 eV respectively - is mature and its efficiency could be enhanced by incorporating subcell(s) with bandgaps of 1 eV and/or 0.7 eV. The Molecular Beam Epitaxy (MBE) growth of such low bandgap materials has thus to be developed, as well as low-resistive tunnel junctions with good structural and optical properties. Based on the MBE growth and the simulation of GaAs tunnel junctions, we have identified interband tunneling as the predominant transport mechanism in such devices rather than trap-assisted-tunneling. The interband tunneling mechanism could be enhanced with the type II GaAsSb/InGaAs heterostructure. Using this material system, we have then demonstrated tunnel junctions with very low electrical resistivity with a limited degradation of the optical and structural properties inherently induced by the use of low band-gap and lattice-mismatched GaAsSb and InGaAs materials. Moreover, we fabricated an innovative AlInGaAs/AlGaAsSb tunnel junction as a graded buffer architecture that could be used for the incorporation of a 1 eV metamorphic subcell. We then developed and characterized InGaAsN(Bi) materials with band-gaps of ~1eV, taking advantage of in-situ wafer curvature measurements during the MBE growth to control the lattice-mismatch. Preliminary solar cells based on GaAs, 1 eV dilute nitride and metamorphic InGaAs have been fabricated and characterized validating the developed tunnel junction architectures. This work has enabled to demonstrate the potential of the type II GaAsSb/InGaAs heterostructure to meet the challenges posed by the conception and the fabrication of GaAs-based MJSCs, both for the tunnel junction and the 1 eV subcell

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Vauthelin, Alexandre. « Fabrication et caractéristiques de cellules photovoltaïques multi-jonctions à base de matériaux antimoniures (III-Sb) pour applications sous fortes concentrations solaires ». Thesis, Montpellier, 2018. http://www.theses.fr/2018MONTS073/document.

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Le développement des systèmes de conversion photovoltaïques ces trente dernières années a permis des améliorations considérables en terme de coût et de performances. A ce jour, les meilleurs rendements de conversion photovoltaïques sont obtenus avec des systèmes à oncentration solaire utilisant des cellules multi-jonctions (MJ) à base de matériaux semi-conducteurs III-V. Dans ce domaine, le meilleur rendement atteint à ce jour est de 46,0 % sous une concentration de 508 soleils avec une cellule à 4 jonctions issu du partenariat Soitec/Fraunhofer ISE/CEA. Cette cellule MJ est composée d’une cellule tandem accordée sur GaAs assemblée par collage moléculaire à une autre cellule tandem accordée sur InP. Bien que le rendement atteint soit élevé, les performances de la cellule sont limitées sous fortes concentrations à cause de ce collage moléculaire. Dans le domaine des fortes concentrations, le record est actuellement détenu par la société américaine Solar Junction avec un rendement de 44,0 % mesuré sur une cellule triple jonction monolithique en GaInP/GaAs/GaInNAs de 0,3 cm² pour un taux de concentration de 942 soleils (irradiance directe de 942 kW/m²). Une seconde cellule a atteint un rendement performant à une irradiance directe supérieure à 1 MW/m², il s’agit d’une cellule tandem en GaInP/GaAs de l’IES-UPM qui a atteint 32,6 % sous une concentration de 1026 soleils.Dans le contexte précédent, les travaux présentés dans ce manuscrit visent à l’évaluation d’une nouvelle filière dans le domaine du CPV à base de semi-conducteurs III-V : la filière antimoniure (III-Sb). Les cellules que nous avons étudiées dans le cadre de cette thèse sont à base de GaSb et de l’alliage AlxGa1-xAsySb1-y, fabriquées de façon monolithique par MBE (Molecular Beam Epitaxy) sur substrat GaSb. Ce type de cellules, du fait de la très bonne complémentarité des gaps des matériaux, constitue une alternative crédible et originale aux cellules existantes pour une utilisation sous flux solaire fortement concentré.Le travail à réaliser dans le cadre de cette thèse porte sur :- La caractérisation électrique et optique des alliages quaternaires utilisés.- La conception et le design des cellules.- La réalisation et la mise au point de toutes les étapes technologiques nécessaires à la conception des cellules (photolithographie UV, gravure, métallisation, …).- La caractérisation électrique et optique des cellules fabriquées (I(V), TLM, réponse spectrale, …).- La caractérisation des cellules sous flux solaire (fortement) concentré.Ce travail a été cofinancé par l’Université de Montpellier et le LabEx SOLSTICE
The development of photovoltaic conversion systems these past thirty years led to considerable improvements in terms of cost and performances. The best conversion efficiencies are currently obtained with solar concentration systems associated with multi-junction solar cells (MJSC) made of III-V materials. In this field, the record efficiency is of 46.0% under a 508-sun solar concentration with a 4-junction cell from Soitec/Fraunhofer ISE/CEA. This MJSC is composed of a tandem cell lattice-matched to GaAs wafer bonded to another tandem cell lattice-matched to InP. Although it reached high conversion efficiency, its performances are limited under solar concentration because of the wafer bonding. In the field of high solar concentrations, the record is held by Solar Junction with a monolithic triple junction GaInP/GaAs/GaInNAs cell of 0.3 cm² that reached an efficiency of 44.0% under 942 suns (direct irradiance of 942 kW/m²). Another high solar concentration efficiency record worth mentioning is held by IES-UPM with a tandem solar cell (GaInP/GaAs) that reached an efficiency of 32.6% under a concentration of 1026 suns.In this context, the work presented in this manuscript aims to evaluate the potential of a new family of III-V materials for high solar concentration applications: antimonide-based materials (III-Sb). The studied cells in this thesis are made out of GaSb and the quaternary AlxGa1-xAsySb1-y, monolithically grown by MBE (Molecular Beam Epitaxy) on a GaSb substrate. These materials, thanks to the large range of available band-gaps, represent an original and well-founded alternative to existing solar cells for high solar concentration applications.The work achieved in this thesis covers:- The electrical and optical characterization of the quaternary materials used.- The conception and designing of the cells.- The production and tuning of every technological steps in order to fabricate our solar cells (UV photolithography, etching, metal deposition,…).- The electrical and optical characterization of our fabricated solar cells (I(V), TLM, spectral response,…).- The characterization under (high) solar concentration of our cells.This work was cofounded by the University of Montpellier and the LabEx SOLSTICE

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Besson, Pierre. « Compréhension des comportements électrique et optique des modules photovoltaïques à haute concentration, et développement d’outils de caractérisations adaptés ». Thesis, Lyon, 2016. http://www.theses.fr/2016LYSEI013/document.

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Le travail de thèse effectué a pour objectif d'amener vers une meilleure compréhension des comportements électrique et optique des modules CPV, dans des conditions environnantes variables. La première partie est consacrée à l’étude de la performance des modules en conditions réelles de fonctionnement. Quatre technologies de module, toutes équipées de cellules triple-jonctions, mais de concentrateurs optiques différents, ont été testées en extérieur sur des périodes de un mois à deux ans. Les résultats montrent que la sensibilité à la température de lentille, la température de cellule et au spectre incident varie selon le type d'architecture optique. La sensibilité la plus importante à la température de lentille a été obtenue pour un dispositif sans optique secondaire. Le coefficient en température de la tension Voc a été calculé et varie entre les technologies. Enfin, les variations importantes de facteur de forme avec le spectre incident observées pour une technologie, mettent en évidence la nécessité d'étudier les phénomènes de non-uniformités d'irradiance sur la cellule. Dans une deuxième partie, le développement d’un banc de test en intérieur permettant de mesurer les performances électriques et optiques est présenté. Ce banc a pour objectif de permettre la reproduction des conditions réelles de fonctionnement des modules de façon contrôlée en intérieur. Un système d’imagerie est utilisé pour déterminer la distribution spatiale et spectrale d’irradiance sur la cellule. Associé à un traceur de courbes IV, il vise à caractériser les effets de flux non-uniformes sur la cellule. Le banc de mesure a pour avantage de découpler les paramètres d’études, telles que la température de la lentille et la température de la cellule, et permet ainsi de décorréler leurs effets respectifs sur l'ensemble optique-cellule, ce qui n’est que difficilement possible sur des mesures en extérieur. Le procédé de calibration et la validation du dispositif sont détaillés dans le manuscrit. Enfin, dans une dernière partie, le banc développé est utilisé pour caractériser trois différents dispositifs CPV : un sans optique secondaire, et deux avec des optiques secondaires différentes. Les impacts de la distance lentille-cellule et de la température de lentille sur les performances de la cellule sont quantifiés optiquement et électriquement. Les résultats montrent comment ces paramètres modifient la distribution de densités de courant des sous-cellules, et donc le comportement électrique du dispositif. Ils soulignent plus spécifiquement comment les non-uniformités spectrales et spatiales affectent les performances de la cellule pour les différents concentrateurs. Le dispositif sans optique secondaire montre une sensibilité importante à la température de la lentille et la distance optique primaire-cellule, qui se traduit par une perte de production d'énergie dans des conditions réelles de fonctionnement
The goal of this doctoral thesis is to bring answers to a better understanding of the electrical and optical behavior of CPV modules, under different operating conditions. In the first part, a study on module performance under real conditions is presented. Using an outdoor automated test bench, the sensitivity of four different CPV module technologies to most operating conditions relevant to CPV systems has been studied, namely DNI, spectrum, cell and lens temperature and clearness of the sky. In order to isolate the influence of a single operation parameter, the analysis of outdoor monitoring data from one month to two years is performed. The results show how the optical design influences the sensitivity of the electrical parameters to the mentionned operating conditions. The effect of lens temperature on cell current has been found to be maximum for the CPV module without Secondary Optical Element. Also the $V_{oc}$ thermal coefficient was found to vary between module technologies. Finally, the important variations of the fill factor for one technology underlines the need of studying non-uniformities effects on the cell performance. According to the results observed outdoors, an indoor tool was developed in order to uncorrelate outdoor parameters. A test bench that measures multi-spectral irradiance profiles, through CMOS imaging and bandpass filters in conjunction with electrical $IV$ curves, is used as a mean to visualize and characterize the effects of chromatic aberrations and nonuniform flux profiles under controllable testing conditions. The bench allows decoupling the temperatures of the Primary Optical Element and cell allowing the analyze of their respective effects on optical and electrical performance. In varying the temperature of the Primary Optical Element, the effects on electrical efficiency, focal distance, spectral sensitivity, acceptance angle, or multi-junction current matching profiles can be quantified. Calibration procedures and validation process are detailed. Finally, the developed testbench is used for analyzing the behvaior of three different CPV devices : one without Secondary Optical Element, and two with different Secondary Optical Elements. The impacts of cell position and lens temperature on the cell performance are quantified optically and electrically. The results show how these parameters modify the current density distribution of the subcells, and hence the electrical behavior of the device. They underline more specifically how spectral and spatial non-uniformities affect the cell performance for the different devices. The device without SOE shows a strong sensitivity to lens temperature and POE-cell distance, that will correspond to a decrease of energy production under real conditions of operation

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Dinca, Dragos. « Development of an Integrated High Energy Density Capture and Storage System for Ultrafast Supply/Extended Energy Consumption Applications ». Cleveland State University / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=csu1495115874616384.

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Zeitouny, Joya. « Advanced strategies for ultra-high PV efficiency ». Thesis, Perpignan, 2018. http://www.theses.fr/2018PERP0056.

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La limite théorique de rendement des cellules photovoltaïques simple-jonction est de l’ordre de 33% d’après le modèle de Shockley-Queisser, ce qui reste éloigné de la limite de Carnot, prédisant une limite maximale de conversion énergie solaire → électricité de 93%. L’écart important entre ces deux limites découle des pertes intrinsèques, essentiellement liées à la conversion inefficace du spectre solaire et à la disparité entre les angles solides d’absorption et d’émission. Pour surmonter ces pertes et se rapprocher de la limite de Carnot, trois stratégies sont envisagées dans cette thèse : les cellules multi-jonction àconcentration, la combinaison de la concentration et de la restriction angulaire et les systèmes hybrides PV/CSP. Chacune de ces stratégies est limitée par des mécanismes qui dégradent leur performance.L’objectif de cette thèse est donc de comprendre dans quelle mesure les différents mécanismes limitants sont susceptibles d’affecter les performances des différentes stratégies étudiées, et d’optimiser l’architecture des cellules dans le but d’accroitre leur efficacité de conversion. Dans ce but, un modèle détaillé de cellule solaire tenant compte des principaux mécanismes limitant a été développé. Un outil d’optimisation par algorithme génétique a également été mis au point, afin d’explorer l’espace des différents paramètres étudiés pour identifier les conditions d’opération optimales. Nous démontrons l’importance majeure que revêt l’adaptation des propriétés optoélectroniques des matériaux utilisés aux conditions opératoires, que ce soit dans le cas des cellules solaires à concentration endurant des pertes résistives significatives, ou encore dans le cas de cellules solaires fonctionnant à des niveaux de températures très supérieurs à l’ambiante. Enfin, nous avons déterminé l’effet des principaux facteurs limitant que constituent les pertes résistives et les recombinaisons non-radiatives sur les cellules solairessimultanément soumises au flux solaire concentré et à la restriction angulaire du rayonnement émis
The maximum efficiency limit attainable with a single-junction PV cell is ~ 33% according to the detailed balance formalism (also known as Shockley-Queisser model), which remains far from the Carnot limit, predicting a solar to electricity efficiency upper value of 93%. The large gap between both limits is due to intrinsic loss mechanisms, including the inefficient conversion of the solar spectrum and the large discrepancy between the solid angles of absorption and emission. To overcome these losses and get closer to the Carnot limit, three different strategies are considered in this thesis: concentrated multi-junction solarcells, the combination of solar concentration and angular confinement, and hybrid PV/CSP systems. Each strategy is inherently limited by several loss mechanisms that degrade their performances. The objective of this thesis is, hence, to better understand the extent to which these strategies are likely to be penalized by these losses, and to tailor the cell properties toward maximizing their efficiencies. To address these questions, a detailed-balance model of PV cell accounting for the main loss mechanisms was developed. A genetic-algorithm optimization tool was also implemented, aiming at exploring the parameter space and identifying the optimal operation conditions. We demonstrate the uttermost importance of tailoring the electronic properties of the materials used with both multi-junction solar cells undergoing significant series resistance losses, and PV cells operating at temperature levels exceeding ambient temperature. We also investigate the extent to which series resistances losses and non-radiative recombination are likely to affect the ability of PV cells simultaneously submitted to concentrated sunlight and angular restriction of the light emitted by band-to-band recombination

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Huang, Jiun-Sung, et 黃俊淞. « Numerical modeling of silicon-based single-junction and multi-junction solar cells ». Thesis, 2011. http://ndltd.ncl.edu.tw/handle/53030387453989508736.

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碩士
國立東華大學
光電工程學系
99
As the quality of life improves, the demand of energy sources of human beings also increases. However, due to the massive consumption of current energy sources on the earth, many different types of renewable energy sources have been developed. Among all the renewable projects in progress, solar energy is the most promising as a future energy technology, because it is the most abundant energy source. In this thesis, we have investigated single junction amorphous solar cells, single junction microcrystalline solar cells, and multi-junction solar cells by the computer simulation tool, Sentaurus TCAD. For an accurate simulation of microcrystalline solar cells, the simulation model considered the grain boundary. In order to absorb wider spectrum of the sun, the concept of multi-junction solar cell was introduced. For reducing the production cost of the manufacturing process, a suitable current matching point is necessary. In the micromorph solar cell, the infrared absorption of microcrystalline silicon is not strong enough. Therefore, adding another lower-bandgap material will compensate the drawback. We used Ge material as the bottom sub-cell in the triple-junction solar cell. The band gap of Ge is 0.66 eV. Therefore, there is effective absorption of infrared in the triple-junction solar cell. In this study, the two junction cell achieved a Jsc of 11.69 mA/cm2, a Voc of 1.50 V, and an efficiency of 10.59 %. Meanwhile, the triple junction achieved a Jsc of 11.30 mA/cm2, a Voc of 1.69 V, and an efficiency of 12.7 %. The results clearly indicated that an additional Ge layer could enhance the Voc of tandem solar cells.

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BAI, WEN-BIN, et 白文賓. « Performance enhancement of single-junction GaAs solar cells ». Thesis, 2018. http://ndltd.ncl.edu.tw/handle/8544hv.

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碩士
國立臺北科技大學
光電工程系
106
In this study, the conversion efficiency of single-junction GaAs solar cells using (a) double layer (ITO/SiO2) anti-reflection and (b) metal/oxide/semiconductor (MOS) structure deposited by thermally RF-sputter were proposed and demonstrated. Optical reflectance, external quantum efficiency, dark current-voltage, and photovoltaic current-voltage of are measured and compared. Type-(a): The optical reflectance of double layer anti-reflection was simulated using TFCalcTM optical thin film software to show a low reflective spectrum at the GaAs solar cells. That in the GaAs solar cells with ITO (41 nm) and SiO2 (58 nm) double-layer anti-reflection layer exhibited the best short circuit current density enhancement, its short circuit current density enhancement (ΔJsc) of 28.43% (from 22.19 mA/cm2 to 28.50 mA/cm2) and conversion efficiency enhancement (Δη) of 30.35% (from 18.78% to 24.48%) were obtained. Type-(b): GaAs solar cells are fabricated using metal-oxide/semiconductor (MOS) structures using Al2O3 or TiO2 as a oxide films, Applying various voltages on the ITO electrode to enhance photovoltaic performance was observed, For the a case of MOS-structure cell, Al2O3/ITO, the short-circuit current density enhancement (ΔJsc) of 15.25% (from 22.69 mA/cm2 to 26.15 mA/cm2) and conversion efficiency enhancement (Δη) of 13.35% (from 18.28% to 20.72%) were obtained; and the oxide layer was TiO2 sputtered ITO transparent electrode (TiO2/ITO), the short-circuit current density enhancement (ΔJsc) of 21.09%(from 23.14 mA/cm2 to 28.02 mA/cm2) and conversion efficiency enhancement (Δη) of 22.40% (from 18.75% to 22.95%) were obtained. To study the biase effection MOS GaAs solar cell, the cell biased at -3.6 V, Jsc of 34.43 mA/cm2, and η of 26.50% foe the cell with Al2O3/ITO were obtained. Similarly, the cell with TiO2/ITO and biased at -3.6 V, Jsc of 36.64 mA/cm2 and η of 28.07% were obtained.

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Wang, Jia-Jiun, et 王家濬. « Manufacturing and Analysis of Hetero-Junction Solar Cells and Single-Crystalline Solar Cells ». Thesis, 2008. http://ndltd.ncl.edu.tw/handle/71620896146909935590.

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碩士
華梵大學
機電工程學系博碩專班
96
Solar cells have the potential to be an important contributor to the global energy demand by the 21-st-century.The dominant topics for solar cell covered in this dissertation are (1) variation in the emitter dopant’s concentration,(2)variation in the wafer dopant’s concentration, (3)variation in the contact resistance,(4)the bifacial light source effects solar cells, (5)design and analysis micro Fresnel lens thin film. This work established a baseline model for silicon based solar cells and from this model the device physics relating to dopant’s concentration, contact resistance, bifacial light source was studied. The micro-Fresnel lens thin film was composed of Fresnel lens, the micro-Fresnel lens thin film has the capability to increase the light utility.

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Chen, Da-Shin, et 陳達欣. « Optimization of Hydrogenated Amorphous Silicon Single-Junction Solar Cells ». Thesis, 2009. http://ndltd.ncl.edu.tw/handle/76430473136478895068.

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碩士
國立交通大學
顯示科技研究所
98
In this study, hydrogenated amorphous silicon (s-Si:H) solar cell was fabricated by plasma enhanced chemical vapor deposition (PECVD). First, we optimized condition of the deposited single layer for p-layer, i-layer and n-layer, respectively. In order to investigate film property, the optoelectronic and optical properties was measured by Fourier Transform Infrared Spectroscopy (FTIR), UV/VIS/NIR spectrometers. The property of hydrogenated amorphous silicon carbide (a-SiC:H) p-layer was measured and discussed. Comparing the photovoltaic performances of the as grown solar cell with p-layer for a-Si:H and a-SiC:H ,respectively. By using wide bandgap p-layer, the open-circuit voltage (Voc) increased from 0.75V to 0.78V with corresponding short-circuit current (Jsc) increased from 10.23mA/cm2 to 12.76mA/cm2. Post-treatment of the cell was also carried out and significant increase in the fill factor (FF), efficiency, and Voc were observed. The experiment result showed an improvement between the Ag back electrode and amorphous n-layer. Different cell area of 2×2 cm2 and 1×1 cm2 were also fabricated. A cell conversion efficiency of 8.67% was achieved for a cell area of 2×2cm2.

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Shih, Zun-Hao, et 施圳豪. « The study of single and dual junction III-V solar cells ». Thesis, 2005. http://ndltd.ncl.edu.tw/handle/u43a33.

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碩士
中原大學
電子工程研究所
93
The object of this study is to fabricate a series interconnected GaAs and InGaP solar cells respectively and particularly focuses on optimizing the most important part of these solar cells, base layer. For semiconductor devices, the carrier concentration influences the electrical properties of the materials. Both the short-circuit current and open-circuit voltage of the solar cell decreases with increasing carrier concentration. In addition, the layer thickness is another essential issue of the output electrical characteristics of device. A thicker layer will absorb more quantity of incident light, but too thick a layer causes an increase in both series resistance and dark current, which will degenerate the performance of the device. We found the optimum values for the thickness and concentration of the device’s active layer through this study. The DJ solar cell is made up of GaAs and InGaP SJ solar cell in series connection. The current mismatching between InGaP and GaAs subcells limits the total photocurrent of the device. We took the results of the SJ solar cell experiments as the references for the DJ solar cell design and the main experiment variable was the base layer thickness of InGaP subcell. By varying base layer thickness and using laser light-bias I-V measurement, one could find the current limited cell clearly and the optimal design of the device. The current-voltage (I-V), external quantum efficiency (EQE) and thermal stability characteristics of the fabricated solar cells were measured by ISO-standard Simulator and homemade spectral response measurement system, respectively, at room and various temperatures.

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Cheng, Po-Hsiang, et 鄭柏翔. « High Efficiency Single-Junction Hydrogenated Amorphous Silicon Thin-Film Solar Cells ». Thesis, 2010. http://ndltd.ncl.edu.tw/handle/05428604144234725853.

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碩士
國立交通大學
光電工程學系
99
In the thesis, device quality hydrogenated amorphous silicon thin film was deposited by plasma enhanced chemical vapor deposition (PECVD) with hydrogen diluted silane. This high quality intrinsic hydrogenated amorphous silicon film was served as the absorber layer in solar cells. When depositing the devices, the electrode spacing and thicknesses of p-type, intrinsic amorphous silicon carbide, intrinsic layer, and n-type amorphous silicon were optimized to be incorporated into the solar cells. Methods of bandgap profiling in the buffer layer between p-layer and i-layer as well as hydrogen plasma treatment at each interface, were applied to optimize the solar cells. As a result, a record solar cell conversion efficiency was enhanced to 9.46%.

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Yang, Chun-Chieh, et 楊竣傑. « Investigation of built-in electric field in single-junction solar cells ». Thesis, 2011. http://ndltd.ncl.edu.tw/handle/47399584457273780620.

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碩士
中原大學
物理研究所
99
This thesis studied the built-in electric field of InGaP solar cells by electroreflectance(ER) measurements. With the increased bias, a decrease of the built-in electric field was found. Using current-voltage characteristics and the built-in electric field as a function of bias, we can get the information about the interface recombination velocity and minority carrier mobility. With the increased illumination power of a laser, a trend of decreasing built-in electric field was found. We fitted built-in electric field as a function of the illumiaiton power by a formula associated with the short-circuit current. Two kinds of GaAs solar cells under different illuminaiton power were measured by ER. The results show that built-in electric field in each GaAs solar cell has been reduced by increasing the illumination power. The decrease of the built-in electric field for these two solar cells was found to be different. Using a formula to fit the experiments, we found that the difference in the decrease of built-in electric fields is due to a difference of reverse saturation current.

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Chen, Guan-Lin, et 陳冠霖. « Optoelectronic Properties of i-Layer Thickness Dependence Single Junction Solar Cells ». Thesis, 2012. http://ndltd.ncl.edu.tw/handle/30452104507069109923.

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碩士
中原大學
電子工程研究所
100
In this thesis, we reported the optoelectronic characteristics of p-i-n GaAs solar cells. We studied the optimum thickness of intrinsic layer for obtaining the highest conversion efficiency. The samples without were detected by current-voltage measurement under AM1.5G illumination that the sample with 1 nm intrinsic layer has the highest efficiency of 14.24％. Based on low temperature photoluminescence and time resolved photoluminescence measurement, localization depth in such intrinsic layer thickness was developed. The experimental result showed that both localization depth (Eloc) at 9.8 meV and radiative lifetime (τrad) at 5.3 ns were achieved the best optoelectronic performance in 1 nm intrinsic layer. It was found out that the localization formed due to Zn diffusion in n-GaAs and intrinsic layer. Different samples annealed at 650℃ with different annealing time were attained to obtain the localization depth. It was clearly revealed that the longer annealed time, leads to the deeper localization, and to the shorter life time. The ECV measurements manifest that the Zn concentrations are changed dramatically. The evidence shows clearly that the Zn presented nominally in the lower n-GaAs and i-GaAs layer, as the result of diffusion. Furthermore, it was proposed to distinguish the front surface recombination velocity from the induced defects by variation the PL intensity. From this photoluminescence measurement, the surface recombination velocity of the solar cells with the intrinsic layer 1 nm is obviously improved. As these results, the thickness of intrinsic layer indeed deeply influences the efficiency of solar cell.

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Hung, Mu-Min, et 洪牧民. « Photovoltaic Characteristics of Single-Junction GaAs Solar Cells with Selective Filter Design ». Thesis, 2014. http://ndltd.ncl.edu.tw/handle/85914213125248536957.

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碩士
國立交通大學
光電工程研究所
103
In detailed balance model, the efficiency of single-junction solar cells can be potentially as high as 33.5% under AM 1.5G illumination. However the best state-of-the-art devices are still far lower than those figures, even the electronic quality is nearly perfect. Therefore the efficiency gap should stem from the light management inside solar cells. Recently, Alta device, Inc. has successfully fabricated a thin-film GaAs single junction solar cell with conversion efficiency of 28.8%, under 1 sun illumination, which aggregates the loss of backward emission into substrate[1]. This factor can be highly relevant to the cell’s performance, especially open-circuit voltage (Voc), and maximizing Voc is generally considered as the last mile to approach ultra-high efficiency limit. In this work, we try to quantify the Voc enhancement in GaAs solar cells by reducing emission loss. The simulation tools are RCWA simulation and photon recycling model NREL developed recently. The top structures we simulate here are different cutoff wavelength thin film selective filter of alternate TiO2 and SiO2. After our calculation, the cutoff wavelength of 840 nm can make the biggest Voc enhancement 36.4meV compared with bare one, and the structure also has excellent anti-reflection ability for maintaining high Jsc. Our results also show that using this way to enhance Voc is especially suitable for cells with ordinary material quality. Therefore, the requests of ideal top structures for solar cells’ use are not only near-perfect anti-reflection, but the ability to minimize the emission loss.

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41

Lu, Wei-Yi, et 呂威毅. « Raman Scattering of i-Layer Thickness Dependence GaAs Single Junction Solar Cells ». Thesis, 2012. http://ndltd.ncl.edu.tw/handle/04836958785003244172.

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碩士
中原大學
電子工程研究所
100
In this thesis we studied the Raman scattering of p-i-n gallium arsenide (GaAs) solar cells with different thicknesses of intrinsic layer. In Raman scattering, used a spatial correlation (SC) model we can explained the correlation length (L) and asymmetry of the longitudinal-optic phonon Raman spectrum. We found the sample with 1 nm thickness of intrinsic layer had the highest correlation length and symmetry. And from current-voltage measurement under AM1.5G illumination that find the highest conversion efficiency (η) in the same sample. Different annealing times 0, 5, 10, 20, 30 and 60 seconds are held at 650 oC in the intrinsic layer 1 nm. symmetric ratio and correlation length are decreased when annealing time is kept from0 to 60 sec. To verify Zn diffusion into the i-layer and base region. We used electrochemical capacitance voltage (ECV) measurement that observe the carrier concentration increased at intrinsic layer and the base region for 60 sec when annealed the 1 nm i-layer GaAs solar cell. The details of the experimental results and the application feasibility of Raman scattering of p-i-n gallium arsenide (GaAs) solar cells with different thicknesses of intrinsic layer in this thesis.

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42

Chih-ShanWu et 吳智善. « The Study of Concentrating Single Junction GaAs Solar Cells With Distributed Bragg Reflector ». Thesis, 2011. http://ndltd.ncl.edu.tw/handle/40319308385614694738.

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43

Hung, Wei-Jie, et 洪偉傑. « Fabrication of Transparent Conductive Oxides for Single-Crystalline n-type Silicon Hetero-Junction Solar Cells ». Thesis, 2010. http://ndltd.ncl.edu.tw/handle/50732695248536570600.

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碩士
華梵大學
機電工程學系博碩專班
98
This paper is aimed to improve the efficiencies of silicon solar cell using semiconductor fabrication technologies. The research first adopts n-type (100) silicon wafers as substrates, and applies KOH etching in the photolithography process to form inverted pyramid structures. The density of the inverse pyramid structures is varied to investigate its impact factor on the reflectivity for the solar cells. In addition, the paper performs high-density plasma chemical vapor deposition to fabricate amorphous silicon thin films. Then, the author can study solar cells performances with single crystal / hydrogenised amorphous silicon heterojunctions, the effects of p-type amorphous silicon films deposited over p-type single crystal films, as well as the influences from p-type amorphous silicon layers and intrinsic layers. Also, the research executes ion implantation to fabricate BSF layers, which are intended to decrease the carrier recombination rate within the interfacing regions, and to improve the minority carrier collection rates. Furthermore, this research employes RF sputtering system to fabricate AZO transparent conductive thin films, and then learns the effects of adjusted processing parameters to the electrical and optical film properties. In the end, hydrogen plasma is used to perform the film post-processing, and the conductive films are then utilized as solar cell electrodes. After using a semiconductor parameter analyzer to perform a series of experimental measurements, the obtained IV curves suggest that the prototyped solar cells can obtain an open circuit voltage Voc = 0.60V, a short circuit current Jsc = 30mA/cm2, a fill factor FF of 62.08%, and an actual efficiency is about 11.13%.

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Lin, Jian-Cheng, et 林建誠. « Conversion Efficiency Enhancement of Single-Junction GaAs Solar Cells Using ITO and Oxide/ITO Films ». Thesis, 2017. http://ndltd.ncl.edu.tw/handle/gzett7.

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碩士
國立臺北科技大學
光電工程系研究所
105
In this study, the conversion efficiency of two types single-junction GaAs solar cell using the antireflective layer of SiO2 , ITO, and SiO2/ITO deposited by thermally RF-sputter was demonstrated. The passivation, antireflection, and biasing effects to enhance the efficiency are characterized. The optical reflectance, external quantum efficiency (EQE), dark current-voltage (I-V), and photovoltaic current-voltage (J-V) are measured and compared. Type-I: Characterization of the single-junction GaAs solar cells with SiO2, ITO, and SiO2/ITO antireflective coating. (1) The bare GaAs solar cell: the open-circuit voltage (Voc) of 1.05V, short-circuit current density (Jsc) of 22.47 mA/cm2 and conversion efficiency (η) of 19.27% were obtained. (2) The GaAs solar cell with a SiO2 (92.71 nm) ARC, Voc of 1.04 V, Jsc of 25.55 mA/cm2, and η of 21.92% were obtained. (3) The GaAs solar cell with an ITO (71.36 nm) ARC, Voc of 1.05 V, Jsc of 27.47 mA/cm2, η of 23.52% were obtained. (4) The GaAs solar cell with a SiO2 (20 nm)/ITO (71.36 nm) ARC, Voc of 1.05 V, Jsc of 27.25 mA/cm2, and η of 23.48% were obtained. Type-II: Characterization of metal-oxide-semiconductor (MOS) structure GaAs solar cells with different oxide materials of SiO2 and SiNx. For MOS structure GaAs solar cell fabrication, SiNx and SiO2 dielectric thin-films are first deposited on the two bare single-junction GaAs solar cells by sputter deposition, respectively. By using photolithography and sputter deposition, the ITO electrode was then formed between the front electrodes upon the surface of dielectric film. (1) The bare GaAs solar cell, Voc of 1.00 V, Jsc of 21.91 mA/cm2, and η of 17.61% were obtained. (2) The GaAs solar cell subsequently deposited 20 nm thick SiNx, Voc of 1.004 V, Jsc of 23.36 mA/cm2, and η of 18.92% were obtained. (3) The GaAs solar cell subsequently deposited ITO transparent electrode (Named as MOS structure GaAs solar cell), Voc of 1.013 V, Jsc of 27.48 mA/cm2, and η of 22.34% were obtained. (4) The MOS GaAs solar cell biased at -3.5 V, Voc of 1.019 V, Jsc of 35.81 mA/cm2, η of 27.04% were obtained. Besides, the MOS GaAs solar cell with the oxide of SiO2, the Jsc of 26.62 mA/cm2 and 36.46 mA/cm2, the η of 21.50% and 26.64% were obtained under 0 V and -3.5 V biasing voltage.

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45

Lin, Yi-Ping, et 林怡萍. « Investigation of Various Methods for Enhancing the Performance of a-Si:H Single-Junction Thin-Film Solar Cells ». Thesis, 2011. http://ndltd.ncl.edu.tw/handle/44793587546675803586.

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碩士
國立交通大學
光電工程學系
100
In this study, hydrogenated amorphous silicon thin-film solar cell was prepared by plasma-enhanced chemical vapor deposition (PECVD) system at 27.12 MHz. In order to improve the cell performance, different materials and structures were prepared to enhance the light absorption in the absorber active layer. First, the lower- refractive-index hydrogenated amorphous silicon nitride (a-SiNx:H) was deposited between the glass substrate and the transparent conductive oxide (TCO) layer to serve as the antireflection (AR) coatings. The performance of the devices having a-SiNx:H with the constant refractive index was compared with the devices having a-SiNx:H with the graded refractive index. The thickness of a-SiNx:H was also adjusted to optimize the performance of solar cells. By inserting 80 nm a-SiNx:H AR coating, a-Si:H single-junction cell had a relative increase of 4.8% in efficiency. Second, devices with different p-type window layers was compared. Hydrogenated microcrystalline silicon (µc-Si:H)/hydrogenated amorphous silicon cabide (a-SiCx:H) and a-SiCx:H/a-SiCx:H double p-layer structures were utilized in devices. The combination of p-layers with better optical and electrical properties was investigated to optimize the cell performance. The efficiency of a-Si:H cells having a-SiCx:H/a-SiCx:H window structure was improved from 9.1% to 9.25%. Finally, the n-doped microcrystalline silicon oxide (µc-SiOx:H(n)) was served as n-layer in solar cells. Besides, µc-SiOx:H(n)/Ag structure was used to replace a-Si:H(n)/TCO/Ag as back reflector (BR) structure. The increase in the optical reflection by the oxide layers on the back side improved the cell performance. The best conversion efficiency in this study was 10.13% with Voc=900.1 mV, Jsc=15.27 mA/cm2, FF=73.75%.

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Su, Yu-Ru, et 蘇郁儒. « Simulation and Analysis of InGaN p-n Single Junction and InGaN/Si p-n Double Junction Solar Cells with Indium Composition and Thickness Dependences ». Thesis, 2011. http://ndltd.ncl.edu.tw/handle/90922207226285283126.

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碩士
國立高雄大學
應用物理學系碩士班
99
InxGa1-xN alloys feature a bandgap ranging from 0.7eV to 3.4eV, covering almost the entire solar spectrum. To optimize the efficiency and the best parameters of solar cells, numerical simulations of InGaN single junction and InGaN/Si double junction solar cells are conducted. The simulation modelling is important and indispensable for designing and fabricating InGaN single junction and InGaN/Si tandem solar cells. We changed the In composition and the thickness of the n- and p-InGaN to determine the short circuit current density (Jsc), open circuit voltage (Voc), fill factor (FF), conversion efficiency (η), and power maximum (Pmax). First, for InGaN single junction solar cell, the Jsc, Voc, and FF have a strong dependence on the In composition. In composition is a critical parameter to determine Jsc, Voc, FF, and η of InGaN solar cells. In0.6Ga0.4N solar cell shows the maximum η ~ 22%. The band gap of In0.6Ga0.4N is 1.42 eV and is almost the same with GaAs. When the total layer thickness is greater than 500 nm, the absorption becomes saturated and the η increases smoothly. The simulation results are congruent with this trend. Second, the p- and n-junction thickness and In composition of InGaN junction are the key point to determine the characteristics of InGaN/Si double junction solar cell. The current matching should be considered in the InGaN/Si double junction solar cells. The smaller Jsc in each junction determines the total Jsc of InGaN/Si double junction solar cell. The total Voc is the sum of the Voc in each junction of InGaN/Si double junction solar cell. Because the current matching affects the Jsc, the curves of the FF have some turning points. The η increases with increasing In content and with dramatically drops with a turning point. With 100 nm p-type InGaN junction, the In0.6Ga0.4N/Si p-n double junction solar cell has the maximum η ~37%. The enhancement of the optimal η of In0.6Ga0.4N/Si p-n double junction solar cell is ~68% higher than that of In0.6Ga0.4N single junction solar cell. The total thickness of InGaN junction must be less than 500 nm, or the most light is absorbed in the InGaN junction and Si junction can not work. The simulation results could provide the clues for optimizing the device structures and process conditions of InGaN single junction and InGaN/Si tandem solar cells.

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47

Yu-ShuenChiu et 邱煜舜. « Study of Various Screen-Printed Pastes for Single- and Multi-crystalline Silicon Solar Cells Applications ». Thesis, 2015. http://ndltd.ncl.edu.tw/handle/jhzxfz.

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博士
國立成功大學
化學系
103
A typical silicon solar cell consists of a p-n junction formed on the surface, a front ohmic contact stripe and fingers, a back contact that covers the entire back surface, and an antireflection coating on the front surface. Screen-printed solar cells are the most widely used cells in the commercial production of silicon solar cells. The key advantage of screen printing is the relative simplicity of the process in spite of its high contact resistance and high shading loss. Commercial mono- and multi-crystalline silicon solar cells use screen-printed process for depositing both the front and rear Ag paste based gridded electrodes, and Al based back whole area metal contacts. Conductive paste usually consists of four constituents: silver or aluminum powder, organic vehicle, glass frit and additive. To date, there have many researchers dedicating to improve the performance of screen-printed front contacts for mono- and multi-crystalline silicon solar cells. This thesis placed more emphasis on the study of the effects of glass frit recipe, silver powder size and temperature on properties. The experimental results show that the welding tension of the front-side electrodes printed by small size silver particle is bigger than that of the front-side electrodes printed by big size silver particles, that is to say, the front-side silver electrode printed by silver paste made of small size silver powder contact very closely with the silicon wafer and have the best welding performance. The rear-side electrode of silver paste prepared by low Tg glass frit has the largest welding tension, and the welding tension of each electrode is uniform. The Al paste/Al-Si eutectic layer/Al-P+ layer (Back-Surface-Field, BSF)/Si(100) stacked structure was obtained by firing the Al paste/Si(100) stacked substrate. A BSF layer can be formed by the regrown silicon due to large amount of Si dissolved in the Al melt. The glass frit layer was formed between the porous Al bulk and the silicon substrate interface after finished contact. Thus, it was difficult to incorporate the Al particles into the silicon substrate through higher Tg of glass frit when the stacked Al paste/Si(100) structure was co-fired at 780 oC. To achieve novel cooling technology for solar module, the performance of screen-printed SiC paste on the back side of solar cell was added. Since SiC has good thermal radiation function, thus its application on PV module can effectively enhance the heat flow from solar cell to back sheet thus increases generation of electricity.

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McPheeters, Claiborne Ott. « The application of light trapping structures and of InGaAs/GaAs quantum wells and quantum dots to improving the performance of single-junction GaAs solar cells ». Thesis, 2012. http://hdl.handle.net/2152/ETD-UT-2012-05-5040.

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High efficiency photovoltaic solar cells are expected to continue to be important for a variety of terrestrial and space power applications. Solar cells made of optically thick materials often cannot meet the cost, efficiency, or physical requirements for specialized applications and, increasingly, for traditional applications. This dissertation investigates improving the performance of single-junction GaAs solar cells by incorporating InGaAs/GaAs quantum wells and quantum dots to increase their spectral response bandwidth, and by incorporating structures that confine light in the devices to improve their absorption of it. InGaAs/GaAs quantum dots-in-wells extend the response of GaAs homojunction devices to wavelengths >1200 nm. Nanoparticles that are randomly deposited on the top of optically thick devices scatter light into waveguide modes of the device structures, increasing their absorption of electromagnetic energy and improving their short-circuit current by up to 16%. Multiply periodic diffractive structures have been optimized using rigorous software algorithms and fabricated on the back sides of thin film quantum dot-in-well solar cells, improving their spectral response at wavelengths 850 nm to 1200 nm, where only the quantum dot-in-well structures absorb light, by factors of up to 10. The improvement results from coupling of diffracted light to waveguide modes of the thin film device structure, and from Fabry-Perot interference effects. Simulations of absorption in these device structures corroborate the measured results and indicate that quantum well solar cells of ~2 µm in thickness, and which are equipped with optimized backside gratings, can achieve 1 Sun Airmass 0 short-circuit current densities of up to ~5 mA/cm2 (15%) greater than GaAs homojunction devices, and of up to >2 mA/cm2 (7%) greater than quantum well devices, with planar back reflectors. A combination of Fabry-Perot interference and diffraction into waveguide modes of the thin devices is shown to dominate the simulated device response spectra. Simulations also demonstrate the importance of low-loss metals for realizing optimal light trapping structures. Such device geometries are promising for reducing the cost of high efficiency solar cells that may be suitable for a variety of traditional and emerging applications.
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Hsiao, Min-Wen, et 蕭閔文. « Improvement of Microcrystalline Silicon Single-Junction and Tandem Solar Cells by Optimizing N-Type Microcrystalline Silicon and Silicon Oxide as Doped and Back Reflecting Layers ». Thesis, 2015. http://ndltd.ncl.edu.tw/handle/krs8f5.

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50

Chen, Jiun-ting, et 陳俊廷. « Investigation of III-V Compounds Multi-Junction Solar Cells ». Thesis, 2007. http://ndltd.ncl.edu.tw/handle/18150150363448353023.

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碩士
國立成功大學
光電科學與工程研究所
95
The purpose of this research is to investigate the passivation mechanism of the window layer (AlInP) of III-V compounds multi-junction solar cells by using (NH4)2Sx solution treatment. The optical and electrical properties of the n-type AlInP layer with and without (NH4)2Sx treatment under different anti-reflection coating (ARC) materials would be analyzed. Besides, the conversion efficiency of the multi-junction solar cell, I-V characteristics (Isc,Voc), series and parallel resistances before and after the (NH4)2Sx treatment would be investigated. Furthermore, the Current-Voltage (I-V) measurement of solar cell would be compared with and without illumination after the (NH4)2Sx treatment. In this experiment, the X-ray photoelectron spectroscopy (XPS) was utilized to analyze the bonding configurations of the n-type AlInP surface before and after the (NH4)2Sx solution treatment. The XPS spectra indicates that In-S bonds can be formed on the AlInP surface after the (NH4)2Sx solution treatment. The S atoms would bond with indium dangling bonds to form In-S bonds to replace the In-O and Al-O bonds which were formed after using the selective etching solution (NH4OH/H2O2/H2O, 1:1:50). The surface state density and surface recombination rate would be reduced after the (NH4)2Sx treatment and the leakage current would be improved. In addition, the Schottky diode and temperature dependent current-voltage (I-V-T) measurements were used to analyze the passivated surface of the AlInP layer. Based on the experimental results, correlations among the bonding configuration, Schottky barrier height and I-V measurement are discussed, which provide the guidelines for the performance provement in the III-V multi-junction solar cells.

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