Dissertations / Theses on the topic 'Plasmonic silicon solar cells'
To see the other types of publications on this topic, follow the link: Plasmonic silicon solar cells.
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 dissertations / theses for your research on the topic 'Plasmonic silicon solar cells.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
1
Crudgington, Lee. "High-performance amorphous silicon solar cells with plasmonic light scattering." Thesis, University of Southampton, 2015. https://eprints.soton.ac.uk/390381/.
Full textAbstract:
This research project is focused on the process optimisation and optical enhancement of the hydrogenated amorphous silicon solar cell design, achieved by the incorporation of light scattering plasmonic nano-particles. These treatments consist of a very thin layer of finely tuned silver metal-island films, which preferentially scatter light within a wavelength range tailored to the device absorption characteristic. This serves to increase the optical path length without the need for surface texturing of the semiconductor material. Within this study, the PECVD process is used to explore the parameter space and fabricate silicon thin films with excellent optical and electrical performance, and a P-I-N amorphous silicon device structure is fabricated with a high performance of 6.5% conversion efficiency, 14.04mA/cm2 current density and 0.82V open circuit voltage. The effects of metallic nano-particle arrays is demonstrated by numerical simulation, showing that variations in particle size, shape, position within the structure and surrounding material greatly influence the enhancement of the nano-particles on silicon absorber layers, and that particles positioned at the rear of the device structure adjacent to a back reflector avoid absorption losses which occur below the particle resonance frequency when such structures are positioned at the front surface. It is shown than an improvement in optical absorption of just over 1% is possible using this method. Silicon thin films are fabricated with self-organised nano-particle arrays via means of annealed metal films, positioned at the front or back adjacent to a metallic reflector, and measurements of optical transmittance, reflectance and absorption are taken. The optimum annealing temperature and duration is identified, and it is shown that these variables can greatly affect the absorption of the device stack. To conclude the study, an amorphous silicon P-I-N photovoltaic device is fabricated featuring self-organised nanoparticle arrays within the back reflector, and a modest improvement of energy conversion efficiency is observed with scope for further optimisation and enhancement.
2
Paetzold, Ulrich W. [Verfasser]. "Light trapping with plasmonic back contacts in thin-film Silicon solar cells / Ulrich Wilhelm Paetzold." Aachen : Hochschulbibliothek der Rheinisch-Westfälischen Technischen Hochschule Aachen, 2013. http://d-nb.info/103710661X/34.
Full text
3
Morawiec, Seweryn. "Self-assembled Plasmonic Nanostructures for Thin Film Photovoltaics." Doctoral thesis, Università di Catania, 2016. http://hdl.handle.net/10761/3971.
Full textAbstract:
The aim of this thesis is to explore the optical properties of localized surface plasmon resonance sustained by self-assembled metallic nanoparticles (NPs) for the light
trapping application in thin lm photovoltaics (PV).
Photovoltaics is able provide safe and clean electricity of the future, inparticular, thin lms solar cells have a potential to increase the competitiveness of PV through a
substantial reduction of the manufacturing cost. However, an essential step it to develop an e cient, reliable and inexpensive light trapping scheme in order to maximize
absorption of the near-infrared radiation in the cell and balance the reduced volume of semiconductor material. Recently there is a growing interest in the application of
subwavelength metallic NPs for light trapping as they can scatter light e ciently over a broad wavelength range of the solar spectrum, due to the to the phenomena known as
localized surface plasmon (LSP) resonance.
A systematic study of the correlation between the structural and the optical properties of self-assembled silver nanostructures fabricated on soda-lime glass by a solid-state dewetting (SSD) process, which consist in thermallyinduced morphology transformation from a thin lm to an array of islands or nanoparticles is reported. It is shown that four distinct types of morphology tend to form in speci c ranges of fabrication parameters, which is quantitatively summarized by a proposed structural-phase diagram and allows to identify the fabrication conditions in which preferable, uniformly spaced and circular NPs are obtainable. The optical properties of the NPs stay in qualitative agreement with the trends predicted by Mie theory, and correlate with the surface coverage (SC) distributions and the mean SC size.
As a step forward towards the implementation in thin lm photovoltaics, the NPs are incorporated on the rear side of thin silicon fillm in two distinct arrangements, namely superstrate and substrate. In superstrate configration,The coupling e ciency increases with NPs' average size, decreases with increasing distance between silicon, and is signi cantly smaller for spherical than for hemispherical NPs, which stay in qualitative agreement with theoretical predictions. A novel procedure, involving a combination of phothermal de
ection spectroscopy and fourier transform photocurrent spectroscopy, employed for substrate con guration lms allowed for the quanti cation of useful and parasitic absorption. It is demonstrated that the optical losses in the NPs are insigni cant in the 500-730nm wavelength range, beyond which they increase rapidly with increasing illumination wavelength. Furthermore, a broadband enhancement of 89.9% of useful absorption has been achieved.
Susequantly, a successful implementation of a plasmonic light trapping scheme implemented in a thin lm a-Si:H solar cell in plasmonic back re
ector (PBR) con guration. The
optical properties of the PBRs are systematically investigated according to the morphology of the self-assembled silver nanoparticles (NPs), which can be tuned by the
fabrication parameters. By analyzing sets of solar cells built on distinct PBRs, it is shown that the photocurrent enhancement achieved in the a-Si:H light trapping window
(600-800 nm) stays in linear relation with the PBRs di use re
ection. The best-performing PBRs allow a pronounced broadband photocurrent enhancement in the cells which is
attributed not only to the plasmon-assisted light scattering from the NPs but also to the front surface texture originated from the conformal growth of the cell material over the particles. As a result, remarkably high values of Jsc and Voc are achieved in comparison to those previously reported in the literature for the same type of devices.
Furthermore an attempt on implementation of the plasmonic light trapping in the industrial a-Si/ c-Si double junction solar cells is reported.
4
Lükermann, Florian [Verfasser]. "Plasmon supported defect absorption in amorphous silicon thin film solar cells and devices / Florian Lükermann." Bielefeld : Universitaetsbibliothek Bielefeld, 2013. http://d-nb.info/1036112136/34.
Full text
5
Li, Xuanhua, and 李炫华. "Plasmonic-enhanced organic solar cells." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2014. http://hdl.handle.net/10722/197526.
Full textAbstract:
Organic solar cells (OSCs) have recently attracted considerable research interest. However, there is a mismatch between their optical absorption length and charge transport scale. Attempts to optimize both the optical and electrical properties of the photoactive layer of OSCs have inevitably resulted in demands for rationally designed device architecture. Plasmonic nanostructures have recently been introduced into solar cells to achieve highly efficient light harvesting. The remaining challenge is to improve OSC performance using plasmonic nanotechnology, a challenge taken up by the research reported in this thesis. I systematically investigated two types of plasmonic effect: localized plasmonic resonances (LPRs) and surface plasmonic resonances (SPRs).
Broadband plasmonic absorption is obviously highly desirable when the LPR effect is adopted in OSCs. Unfortunately, typical nanomaterials possess only a single resonant absorption peak, which inevitably limits the power conversion efficiency (PCE) enhancement to a narrow spectral range. To address this issue, I combined Ag nanomaterials of different shapes, including nanoparticles and nanoprisms. The incorporation of these mixed nanomaterials into the active layer resulted in wide band absorption improvement. My results suggest a new approach to achieving greater overall enhancement through an improvement in broadband absorption.
I also explored the SPR effect induced by a metal patterned electrode with two parts. Most reports to date on back reflector realization involve complicated and costly techniques. In this research, however, I adopted a polydimethylsiloxane (PDMS)-nanoimprinted method to produce patterned back electrodes in OSCs directly, which is a very simple and efficient technique for realizing high-performance OSCs in industrial processes. Besides, a remaining challenge is that plasmonic effects are strongly sensitive to light polarization, which limits plasmonic applications in practice. To address this issue, I designed three-dimensional patterns as the back electrode of inverted OSCs, which simultaneously achieved highly efficient and polarization-independent plasmonic OSCs.
In addition to investigating the two types of plasmonic effect individually, I also investigated their integrated function by introducing both LPRs and SPRs in one device structure. With the aim of achieving high-performance OSCs, I first demonstrated experimentally a dual metal nanostructure composed of Au nanoparticles (i.e. LPRs) embedded in the active layer and an Ag nanograting electrode (i.e. SPRs) as the back reflectors in inverted OSCs, which can generate a very strong electric field, in a single junction to improve the light absorption of solar cells. As a result, the PCE of the OSC reached 9.1%, making it one of the best-performing OSCs reported to date. In addition, as an important extension, I subsequently achieved tremendous near-field enhancement owing to multiple couplings, including nanoparticle-nanoparticle (LPR-LPR) couplings and nanoparticle-film (LPR-SPR) couplings, by designing a novel nanoparticle-film coupling system through the introduction of ultrathin monolayer graphene as a well-defined sub-nanogap between the Ag nanoparticles and Ag film. The graphene sub-nanogap is the thinnest nanogap (in atomic scale terms) to date, and thus constitutes a promising light-trapping strategy for improving future OSC performance.published_or_final_version
Electrical and Electronic Engineering
Doctoral
Doctor of Philosophy
6
Lal, Niraj Narsey. "Enhancing solar cells with plasmonic nanovoids." Thesis, University of Cambridge, 2012. https://www.repository.cam.ac.uk/handle/1810/243864.
Full textAbstract:
This thesis explores the use of plasmonic nanovoids for enhancing the efficiency of thin-film solar cells. Devices are fabricated inside plasmonically resonant nanostructures, demonstrating a new class of plasmonic photovoltaics. Novel cell geometries are developed for both organic and amorphous silicon solar cell materials. An external-quantum efficency rig was set up to allow simultaneous microscope access and micrometer-precision probe-tip control for optoelectronic characterisation of photovoltaic devices. An experimental setup for angle-resolved re ectance was extended to allow broadband illumination from 380 - 1500nm across incident angles 0 - 70 degrees giving detailed access to the energy-momentum dispersion of optical modes within nanostructured materials. A four-fold enhancement of overall power conversion efficiency is observed in organic nanovoid solar cells compared to at solar cells. The efficiency enhancement is shown to be primarily due to strong localised plasmon resonances of the nanovoid geometry, with close agreement observed between experiment and theoretical simulations. Ultrathin amorphous silicon solar cells are fabricated on both nanovoids and randomly textured silver substrates. Angle-resolved re ectance and computational simulations highlight the importance of the spacer layer separating the absorbing and plasmonic materials. A 20% enhancement of cell efficiency is observed for nanovoid solar cells compared to at, but with careful optimisation of the spacer layer, randomly textured silver allows for an even greater enhancement of up to 50% by controlling the coupling to optical modes within the device. The differences between plasmonic enhancement for organic and amorphous silicon solar cells are discussed and the balance of surface plasmon absorption between a semiconductor and a metal is analytically derived for a broad range of solar cell materials, yielding clear design principles for plasmonic enhancement. These principles are used to outline future directions of research for plasmonic photovoltaics.
7
Cao, Zhixiong. "Silver nanoprisms in plasmonic organic solar cells." Thesis, Ecole centrale de Marseille, 2014. http://www.theses.fr/2014ECDM0015/document.
Full textAbstract:
On constate une forte demande mondiale d' énergie propre et renouvelable en raison de la consommation rapide des combustibles fossiles non renouvelables et l'effet de serre qui en résulte. Une solution prometteuse pour produire une énergie propre et renouvelable est d'utiliser des cellules solaires pour convertir l' énergie solaire directement en électricité. Comparativement à leurs homologues inorganiques, les cellules solaires organiques (OSCs) sont maintenant intensivement étudiées en raison des avantages tels que le poids léger, la flexibilité, la compatibilité avec les procédés de fabrication à faibles coûts. Malgré ces avantages, l'efficacité de conversion (PCE) des OSCs doit encore être améliorée pour la commercialisation à grande échelle. Les cellules solaires organiques sont réalisées en pile de couches minces comprenant des électrodes, la couche de transport d' électrons, la couche de polymère actif et la couche de transport de trous. Dans cette étude, nous sommes concernés par la couche de PEDOT:PSS qui est couramment utilisée comme une couche tampon entre l'électrode anodique et la couche de polymère actif de cellules solaires organiques. Cette étude vise à intégrer différentes concentrations de nanoprismes (NPSMs) d'argent de taille sub-longueur d'onde dans du PEDOT: PSS afin de profiter de leurs propriétés optiques uniques nées de résonances de plasmons de surface localisées (LSPR) pour améliorer la collecte lumineuse et l'efficacité de génération de charge en optimisant l' absorption et la diffusion de la lumière. Nous avons constaté que les facteurs clés qui contrôlent les performances des cellules solaires plasmoniques comprennent non seulement les propriétés optiques, mais également les propriétés structurelles et électriques des couches hybrides de PEDOT:PSS comprenant des NPSMs d' Ag. D'une part, l'ajout de NPSMs d' Ag conduit ¨¤ (1) une augmentation de l'absorption optique; (2) de la diffusion de la lumière ¨¤ de grands angles ce qui pourrait conduire ¨¤ un meilleur piégeage de la lumière dans les OSCs. D'autre part, (1) la rugosité de surface est augment¨¦e en raison de la formation d'agglomérats de NPSMs d' Ag, ce qui conduit ¨¤ une meilleure efficacité de collecte de charge; (2) la résistance globale des films hybrides est également augment¨¦e en raison de l'excès de PSS introduit par les NPSMs d' Ag incomplètement purifiées, inférieur courant de court-circuit (Jsc) qui en résulte; (3) les Ag NPSMs et leurs agglomérats ¨¤ l'interface PEDOT:PSS/couche photo-active pourraient agir comme des centres de recombinaison, conduisant ¨¤ une réduction de la résistance de shunt, du Jsc et de la tension en circuit ouvert (Voc). Afin de résoudre partiellement l'inconvénient (2) et (3), en intégrant des NPSMs d¡¯Ag davantage purifiés et une petite quantité de glycérol dans le PEDOT:PSS, la résistance des couches hybrides de PEDOT:PSS-Ag-NPSMs peut ¨être réduite à une valeur comparable ou inférieure ¨¤ celles couches vierges. Les futurs progrès en chimie de surface colloïdale et l'optimisation sur le processus d'incorporation des nanoparticules seront nécessaires pour produire des cellules solaires organiques plasmoniques de meilleures performancesNowadays there has been a strong global demand for renewable and clean energy due to the rapid consumption of non-renewable fossil fuels and the resulting greenhouse effect. One promising solution to harvest clean and renewable energy is to utilize solar cells to convert the energy of sunlight directly into electricity. Compared to their inorganic counterparts, organic solar cells (OSCs) are now of intensive research interest due to advantages such as light weight, flexibility, the compatibility to low-cost manufacturing processes. Despite these advantages, the power conversion efficiency (PCE) of OSCs still has to be improved for large-scale commercialization. OSCs are made of thin film stacks comprising electrodes, electron transporting layer, active polymer layer and hole transporting layer. In this study, we are concerned with PEDOT:PSS layer which is commonly used as a buffer layer between the anodic electrode and the organic photoactive layer of the OSC thin film stack. We incorporated different concentrations of silver nanoprisms (NPSMs) of sub-wavelength dimension into PEDOT:PSS. The purpose is to take advantage of the unique optical properties of Ag MPSMs arisen from localized surface plasmon resonance (LSPR) to enhance the light harvest and the charge generation efficiency by optimizing absorption and scattering of light in OSCs. We found that the key factors controlling the device performance of plasmonic solar cells include not only the optical properties but also the structural and electrical properties of the resulting hybrid PEDOT:PSS-Ag-NPSM-films. On one hand, the addition of Ag NPSMs led to (1) an increased optical absorption; (2) light scattering at high angles which could possibly lead to more efficient light harvest in OSCs. On the other hand, the following results have been found in the hybrid films: (1) the surface roughness was found to be increased due to the formation of Ag agglomerates, leading to increased charge collection efficiency; (2) the global sheet resistance of the hybrid films also increases due to the excess poly(sodium styrenesulphonate) introduced by incompletely purified Ag NPSMs, resulting in lower short circuit current (Jsc); (3) the Ag nanoprisms and their agglomerates at the PEDOT:PSS/photoactive layer interface could act as recombination centers, leading to reductions in shunt resistance, Jsc and open circuit voltage (Voc). In order to partially counteract the disadvantage (2) and (3), by incorporating further purified Ag NPSMs and/or a small amount of glycerol into PEDOT:PSS, the sheet resistance of hybrid PEDOT:PSS-Ag-NPSM-films was reduced to a resistance value comparable to or lower than that of pristine film
8
Søiland, Anne Karin. "Silicon for Solar Cells." Doctoral thesis, Norwegian University of Science and Technology, Department of Materials Technology, 2005. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-565.
Full textAbstract:
This thesis work consists of two parts, each with a different motivation. Part II is the main part and was partly conducted in industry, at ScanWafer ASA’s plant no.2 in Glomfjord.
The large growth in the Photo Voltaic industry necessitates a dedicated feedstock for this industry, a socalled Solar Grade (SoG) feedstock, since the currently used feedstock rejects from the electronic industry can not cover the demand. Part I of this work was motivated by this urge for a SoG- feedstock. It was a cooperation with the Sintef Materials and Chemistry group, where the aim was to study the kinetics of the removal reactions for dissolved carbon and boron in a silicon melt by oxidative gas treatment. The main focus was on carbon, since boron may be removed by other means. A plasma arc was employed in combination with inductive heating. The project was, however, closed after only two experiments. The main observations from these two experiments were a significant boron removal, and the formation of a silica layer on the melt surface when the oxygen content in the gas was increased from 2 to 4 vol%. This silica layer inhibited further reactions.
Multi-crystalline (mc) silicon produced by directional solidification constitutes a large part of the solar cell market today. Other techniques are emerging/developing and to keep its position in the market it is important to stay competitive. Therefore increasing the knowledge on the material produced is necessary. Gaining knowledge also on phenomenas occurring during the crystallisation process can give a better process control.
Part II of this work was motivated by the industry reporting high inclusion contents in certain areas of the material. The aim of the work was to increase the knowledge of inclusion formation in this system. The experimental work was divided into three different parts;
1) Inclusion study
2) Extraction of melt samples during crystallisation, these were to be analysed for carbon- and nitrogen. Giving thus information of the contents in the liquid phase during soldification.
3) Fourier Transform Infrared Spectroscopy (FTIR)-measurements of the substitutional carbon contents in wafers taken from similar height positions as the melt samples. Giving thus information of the dissolved carbon content in the solid phase.
The inclusion study showed that the large inclusions found in this material are β-SiC and β-Si3N4. They appear in particularly high quantities in the top-cuts. The nitrides grow into larger networks, while the carbide particles tend to grow on the nitrides. The latter seem to act as nucleating centers for carbide precipitation. The main part of inclusions in the topcuts lie in the size range from 100- 1000 µm in diameter when measured by the Coulter laser diffraction method.
A method for sampling of the melt during crystallisation under reduced pressure was developed, giving thus the possibility of indicating the bulk concentration in the melt of carbon and nitrogen. The initial carbon concentration was measured to ~30 and 40 ppm mass when recycled material was employed in the charge and ~ 20 ppm mass when no recycled material was added. Since the melt temperature at this initial stage is ~1500 °C these carbon levels are below the solubility limit. The carbon profiles increase with increasing fraction solidified. For two profiles there is a tendency of decreasing contents at high fraction solidified.
For nitrogen the initial contents were 10, 12 and 44 ppm mass. The nitrogen contents tend to decrease with increasing fraction solidified. The surface temperature also decreases with increasing fraction solidified. Indicating that the melt is saturated with nitrogen already at the initial stage. The proposed mechanism of formation is by dissolution of coating particles, giving a saturated melt, where β-Si3N4 precipitates when cooling. Supporting this mechanism are the findings of smaller nitride particles at low fraction solidified, that the precipitated phase are β-particles, and the decreasing nitrogen contents with increasing fraction solidified.
The carbon profile for the solid phase goes through a maximum value appearing at a fraction solidified from 0.4 to 0.7. The profiles flatten out after the peak and attains a value of ~ 8 ppma. This drop in carbon content is associated with a precipitation of silicon carbide. It is suggested that the precipitation of silicon carbide occurs after a build-up of carbon in the solute boundary layer.
FTIR-measurements for substitutional carbon and interstitial oxygen were initiated at the institute as a part of the work. A round robin test was conducted, with the Energy Research Centre of the Netherlands (ECN) and the University of Milano-Bicocci (UniMiB) as the participants. The measurements were controlled against Secondary Ion Mass Spectrometer analyses. For oxygen the results showed a good correspondence between the FTIR-measurements and the SIMS. For carbon the SIMS-measurements were significantly lower than the FTIR-measurements. This is probably due to the low resistivity of the samples (~1 Ω cm), giving free carrier absorption and an overestimation of the carbon content.
9
Essner, Jeremy. "Dye sensitized solar cells: optimization of Grätzel solar cells towards plasmonic enhanced photovoltaics." Thesis, Kansas State University, 2011. http://hdl.handle.net/2097/12416.
Full textAbstract:
Master of ScienceDepartment of Chemistry
Jun Li
With the worldly consumption of energy continually increasing and the main source of this energy, fossil fuels, slowly being depleted, the need for alternate sources of energy is becoming more and more pertinent. One promising approach for an alternate method of producing energy is using solar cells to convert sunlight into electrical energy through photovoltaic processes. Currently, the most widely commercialized solar cell is based on a single p-n junction with silicon. Silicon solar cells are able to obtain high efficiencies but the downfall is, in order to achieve this performance, expensive fabrication techniques and high purity materials must be employed. An encouraging cheaper alternative to silicon solar cells is the dye-sensitized solar cell (DSSC) which is based on a wide band gap semiconductor sensitized with a visible light absorbing species. While DSSCs are less expensive, their efficiencies are still quite low compared to silicon. In this thesis, Grätzel cells (DSSCs based on TiO2 NPs) were fabricated and optimized to establish a reliable standard for further improvement. Optimized single layer GSCs and double layer GSCs showing efficiencies >4% and efficiencies of ~6%, respectively, were obtained. Recently, the incorporation of metallic nanoparticles into silicon solar cells has shown improved efficiency and lowered material cost. By utilizing their plasmonic properties, incident light can be scattered, concentrated, or trapped thereby increasing the effective path length of the cell and allowing the physical thickness of the cell to be reduced. This concept can also be applied to DSSCs, which are cheaper and easier to fabricate than Si based solar cells but are limited by lower efficiency. By incorporating 20 nm diameter Au nanoparticles (Au NPs) into DSSCs at the FTO/TiO2 interface as sub wavelength antennae, average photocurrent enhancements of 14% (maximum up to ~32%) and average efficiency enhancements of 13% (maximum up to ~23% ) were achieved with well dispersed, low surface coverages of nanoparticles. However the Au nanoparticle solar cell (AuNPSC) performance is very sensitive to the surface coverage, the extent of nanoparticle aggregation, and the electrolyte employed, all of which can lead to detrimental effects (decreased performances) on the devices.
10
Uprety, Prakash. "Plasmonic Enhancement in PbS Quantum Dot Solar Cells." Bowling Green State University / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1403022047.
Full text
11
Tarabsheh, Anas al. "Amorphous silicon based solar cells." kostenfrei, 2007. http://nbn-resolving.de/urn:nbn:de:bsz:93-opus-29491.
Full text
12
Al, Tarabsheh Anas. "Amorphous silicon based solar cells." [S.l. : s.n.], 2007. http://nbn-resolving.de/urn:nbn:de:bsz:93-opus-29491.
Full text
13
Bett, Alexander Jürgen [Verfasser], and Stefan [Akademischer Betreuer] Glunz. "Perovskite silicon tandem solar cells : : two-terminal perovskite silicon tandem solar cells using optimized n-i-p perovskite solar cells." Freiburg : Universität, 2020. http://d-nb.info/1214179703/34.
Full text
14
Saliba, Michael. "Plasmonic nanostructures and film crystallization in perovskite solar cells." Thesis, University of Oxford, 2014. http://ora.ox.ac.uk/objects/uuid:fdb36a9e-ddf5-4d27-a8dc-23fffe32a2c5.
Full textAbstract:
The aim of this thesis is to develop a deeper understanding and the technology in the nascent field of solid-state organic-inorganic perovskite solar cells. In recent years, perovskite materials have emerged as a low-cost, thin-film technology with efficiencies exceeding 16% challenging the quasi-paradigm that high efficiency photovoltaics must come at high costs. This thesis investigates perovskite solar cells in more detail with a focus on incorporating plasmonic nanostructures and perovskite film formation. Chapter 1 motivates the present work further followed by Chapter 2 which offers a brief background for solar cell fabrication and characterisation, perovskites in general, perovskite solar cells in specific, and plasmonics. Chapter 3 presents the field of plasmonics including simulation methods for various core-shell nanostructures such as gold-silica and silver-titania nanoparticles. The following Chapters 4 and 5 analyze plasmonic core-shell metal-dielectric nanoparticles embedded in perovskite solar cells. It is shown that using gold@silica or silver@titania NPs results in enhanced photocurrent and thus increased efficiency. After photoluminescence studies, this effect was attributed to an unexpected phenomenon in solar cells in which a lowered exciton binding energy generates a higher fraction of free charge. Embedding thermally unstable silver NPs required a low-temperature fabrication method which would not melt the Ag NPs. This work offers a new general direction for temperature sensitive elements. In Chapters 6 and 7, perovskite film formation is studied. Chapter 6 shows the existence of a previously unknown crystalline precursor state and an improved surface coverage by introducing a ramped annealing procedure. Based on this, Chapter 7 investigates different perovskite annealing protocols. The main finding was that an additional 130°C flash annealing step changed the film crystallinity dramatically and yielded a higher orientation of the perovskite crystals. The according solar cells showed an increased photocurrent attributed to a decrease in charge carrier recombination at the grain boundaries. Chapter 8 presents on-going work showing noteworthy first results for silica scaffolds, and layered, 2D perovskite structures for application in solar cells.
15
Schultz, Oliver. "High-efficiency multicrystalline silicon solar cells." München Verl. Dr. Hut, 2005. http://deposit.d-nb.de/cgi-bin/dokserv?idn=977880567.
Full text
16
Echeverria, Molina Maria Ines. "Crack Analysis in Silicon Solar Cells." Scholar Commons, 2012. http://scholarcommons.usf.edu/etd/4311.
Full textAbstract:
Solar cell business has been very critical and challenging since more efficient and low costs materials are required to decrease the costs and to increase the production yield for the amount of electrical energy converted from the Sun's energy. The silicon-based solar cell has proven to be the most efficient and cost-effective photovoltaic industrial device. However, the production cost of the solar cell increases due to the presence of cracks (internal as well as external) in the silicon wafer. The cracks of the wafer are monitored while fabricating the solar cell but the present monitoring techniques are not sufficient when trying to improve the manufacturing process of the solar cells. Attempts are made to understand the location of the cracks in single crystal and polycrystalline silicon solar cells, and analyze the impact of such cracks in the performance of the cell through Scanning Acoustic Microscopy (SAM) and Photoluminescence (PL) based techniques.
The features of the solar cell based on single crystal and polycrystalline silicon through PL and SAM were investigated with focused ion beam (FIB) cross section and scanning electron microscopy (SEM). The results revealed that SAM could be a reliable method for visualization and understanding of cracks in the solar cells.
The efficiency of a solar cell was calculated using the current (I) - voltage (V) characteristics before and after cracking of the cell. The efficiency reduction ranging from 3.69% to 14.73% for single crystal, and polycrystalline samples highlighted the importance of the use of crack monitoring techniques as well as imaging techniques. The aims of the research are to improve the manufacturing process of solar cells by locating and understanding the crack in single crystal and polycrystalline silicon based devices.
17
Li, Dai-Yin. "Texturization of multicrystalline silicon solar cells." Thesis, Massachusetts Institute of Technology, 2010. http://hdl.handle.net/1721.1/64615.
Full textAbstract:
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2010.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 103-111).
A significant efficiency gain for crystalline silicon solar cells can be achieved by surface texturization. This research was directed at developing a low-cost, high-throughput and reliable texturing method that can create a honeycomb texture. Two distinct approaches for surface texturization were studied. The first approach was photo-defined etching. For this approach, the research focus was to take advantage of Vall6ra's technique published in 1999, which demonstrated a high-contrast surface texture on p-type silicon created by photo-suppressed etching. Further theoretical consideration, however, led to a conclusion that diffusion of bromine in the electrolyte impacts the resolution achievable with Vallera's technique. Also, diffusion of photocarriers may impose an additional limitation on the resolution. The second approach studied was based on soft lithography. For this approach, a texturization process sequence that created a honeycomb texture with 20 ptm spacing on polished wafers at low cost and high throughput was developed. Novel techniques were incorporated in the process sequence, including surface wettability patterning by microfluidic lithography and selective condensation based on Raoult's law. Microfluidic lithography was used to create a wettability pattern from a 100A oxide layer, and selective condensation based on Raoult's law was used to reliably increase the thickness of the glycerol/water liquid film entrained on hydrophilic oxide islands approximately from 0.2 pm to 2.5 pm . However, there remain several areas that require further development to make the process sequence truly successful, especially when applied to multicrystalline wafers.
by Dai-Yin Li.
Ph.D.
18
Osorio, Ruy Sebastian Bonilla. "Surface passivation for silicon solar cells." Thesis, University of Oxford, 2015. https://ora.ox.ac.uk/objects/uuid:46ebd390-8c47-4e4b-8c26-e843e8c12cc4.
Full textAbstract:
Passivation of silicon surfaces remains a critical factor in achieving high conversion efficiency in solar cells, particularly in future generations of rear contact cells -the best performing cell geometry to date. In this thesis, passivation is characterised as either intrinsic or extrinsic, depending on the origin of the chemical and field effect passivation components in dielectric layers. Extrinsic passivation, obtained after film deposition or growth, has been shown to improve significantly the passivation quality of dielectric films. Record passivation has been achieved leading to surface recombination velocities below 1.5 cm/s for 1 Ωcm n-type silicon covered with thermal oxide, and 0.15 cm/s in the same material covered with a thermal SiO2/PECVD SiNx double layer. Extrinsic field effect passivation, achieved by means of corona charge and/or ionic species, has been shown to decrease by 3 to 10 times the amount of carrier recombination at a silicon surface. A new parametrisation of interface charge, and electron and hole recombination velocities in a Shockley-Read-Hall extended formalism has been used to model accurately silicon surface recombination without the need to incorporate a term relating to space-charge or surface damage recombination. Such a term is unrealistic in the case of an oxide/silicon interface. A new method to produce extrinsic field effect passivation has been developed in which charge is introduced into dielectric films at high temperature and then permanently quenched in place by cooling to room temperature. This approach was investigated using charge due to one or more of the following species: ions produced by corona discharge, Na+, K+, Cs+, Mg2+ and Ca2+. It was implemented on both single SiO2 and double SiO2/SiNx dielectric layers which were then measured for periods of up to two years. The decay of the passivation was very slow and time constants of the order of 10,000 days were inferred for two systems: 1) corona-charge-embedded into oxide grown on textured FZ-Si, and 2) potassium ions driven into an oxide on planar FZ-Si. The extrinsic field effect passivation methods developed in this work allow more flexibility in the combined optimisation of the optical properties and the chemical passivation properties of dielectric films on semiconductors. Increases in cell Voc, Jsc and η parameters have been observed in simulations and obtained experimentally when extrinsic field effect passivation is applied to the front surface of silicon solar cells. The extrinsic passivation reported here thus represents a major advancement in controlled and stable passivation of silicon surfaces, and shows great potential as a scalable and cost effective passivation technology for solar cells.
19
Zhu, Mingxuan. "Silicon nanowires for hybrid solar cells." Ecole centrale de Marseille, 2013. http://tel.archives-ouvertes.fr/docs/00/94/57/87/PDF/The_manuscript-4.pdf.
Full text
20
Forster, Maxime. "Compensation engineering for silicon solar cells." Phd thesis, INSA de Lyon, 2012. http://hdl.handle.net/1885/156020.
Full textAbstract:
This thesis focuses on the effects of dopant compensation on the electrical properties of crystalline silicon relevant to the operation of solar cells. We show that the control of the net dopant density, which is essential to the fabrication of high-efficiency solar cells, is very challenging in ingots crystallized with silicon feedstock containing both boron and phosphorus such as upgraded metallurgical-grade silicon. This is because of the strong segregation of phosphorus which induces large net dopant density variations along directionally solidified silicon crystals. To overcome this issue, we propose to use gallium co-doping during crystallization, and demonstrate its potential to control the net dopant density along p-type and n-type silicon ingots grown with silicon containing boron and phosphorus. The characteristics of the resulting highly-compensated material are identified to be: a strong impact of incomplete ionization of dopants on the majority carrier density, an important reduction of the mobility compared to theoretical models and a recombination lifetime which is determined by the net dopant density and dominated after long-term illumination by the boron-oxygen recombination centre. To allow accurate modelling of upgraded-metallurgical silicon solar cells, we propose a parameterization of these fundamental properties of compensated silicon. We study the light-induced lifetime degradation in p-type and n-type Si with a wide range of dopant concentrations and compensation levels and show that the boron-oxygen defect is a grown-in complex involving substitutional boron and is rendered electrically active upon injection of carriers through a charge-driven reconfiguration of the defect. Finally, we apply gallium co-doping to the crystallization of upgraded-metallurgical silicon and demonstrate that it allows to significantly increase the tolerance to phosphorus without compromising neither the ingot yield nor the solar cells performance before light-induced degradation.
21
Forster, Maxime. "Compensation engineering for silicon solar cells." Phd thesis, INSA de Lyon, 2012. http://tel.archives-ouvertes.fr/tel-00876318.
Full textAbstract:
This thesis focuses on the effects of dopant compensation on the electrical properties of crystalline silicon relevant to the operation of solar cells. We show that the control of the net dopant density, which is essential to the fabrication of high-efficiency solar cells, is very challenging in ingots crystallized with silicon feedstock containing both boron and phosphorus such as upgraded metallurgical-grade silicon. This is because of the strong segregation of phosphorus which induces large net dopant density variations along directionally solidified silicon crystals. To overcome this issue, we propose to use gallium co-doping during crystallization, and demonstrate its potential to control the net dopant density along p-type and n-type silicon ingots grown with silicon containing boron and phosphorus. The characteristics of the resulting highly-compensated material are identified to be: a strong impact of incomplete ionization of dopants on the majority carrier density, an important reduction of the mobility compared to theoretical models and a recombination lifetime which is determined by the net dopant density and dominated after long-term illumination by the boron-oxygen recombination centre. To allow accurate modelling of upgraded-metallurgical silicon solar cells, we propose a parameterization of these fundamental properties of compensated silicon. We study the light-induced lifetime degradation in p-type and n-type Si with a wide range of dopant concentrations and compensation levels and show that the boron-oxygen defect is a grown-in complex involving substitutional boron and is rendered electrically active upon injection of carriers through a charge-driven reconfiguration of the defect. Finally, we apply gallium co-doping to the crystallization of upgraded-metallurgical silicon and demonstrate that it allows to significantly increase the tolerance to phosphorus without compromising neither the ingot yield nor the solar cells performance before light-induced degradation.
22
McCann, Michelle Jane, and michelle mccann@uni-konstanz de. "Aspects of Silicon Solar Cells: Thin-Film Cells and LPCVD Silicon Nitride." The Australian National University. Faculty of Engineering and Information Technology, 2002. http://thesis.anu.edu.au./public/adt-ANU20040903.100315.
Full textAbstract:
This thesis discusses the growth of thin-film silicon layers suitable for solar cells using
liquid phase epitaxy and the behaviour of oxide LPCVD silicon nitride stacks on silicon
in a high temperature ambient.¶
The work on thin film cells is focussed on the characteristics of layers grown using liquid
phase epitaxy. The morphology resulting from different seeding patterns, the transfer of
dislocations to the epitaxial layer and the lifetime of layers grown using oxide compared
with carbonised photoresist barrier layers are discussed. The second half of this work
discusses boron doping of epitaxial layers. Simultaneous layer growth and boron doping
is demonstrated, and shown to produce a 35um thick layer with a back surface field
approximately 3.5um thick.¶
If an oxide/nitride stack is formed in the early stages of cell processing, then characteristics of the nitride may enable increased processing flexibility and hence the realisation
of novel cell structures. An oxide/nitride stack on silicon also behaves as a good anti-
reflection coating. The effects of a nitride deposited using low pressure chemical vapour
deposition on the underlying wafer are discussed. With a thin oxide layer between the
silicon and the silicon nitride, deposition is shown not to significantly alter effective life-times.¶
Heating an oxide/nitride stack on silicon is shown to result in a large drop in effective
Lifetimes. As long as at least a thin oxide is present, it is shown that a high temperature
nitrogen anneal results in a reduction in surface passivation, but does not significantly
affect bulk lifetime. The reduction in surface passivation is shown to be due to a loss of
hydrogen from the silicon/silicon oxide interface and is characterised by an increase in
Joe. Higher temperatures, thinner oxides, thinner nitrides and longer anneal times are all
shown to result in high Joe values. A hydrogen loss model is introduced to explain the
observations.¶
Various methods of hydrogen re-introduction and hence Joe recovery are then discussed
with an emphasis on high temperature forming gas anneals. The time necessary
for successful Joe recovery is shown to be primarily dependent on the nitride thickness
and on the temperature of the nitrogen anneal. With a high temperature forming gas
anneal, Joe recovery after nitrogen anneals at both 900 and 1000oC and with an optimised
anti-reflection coating is demonstrated for chemically polished wafers.¶
Finally the effects of oxide/nitride stacks and high temperature anneals in both nitrogen
and forming gas are discussed for a variety of wafers. The optimal emitter sheet
resistance is shown to be independent of nitrogen anneal temperature. With textured
wafers, recovery of Joe values after a high temperature nitrogen anneal is demonstrated
for wafers with a thick oxide, but not for wafers with a thin oxide. This is shown to be
due to a lack of surface passivation at the silicon/oxide interface.
23
Chen, Wan Lam Florence Photovoltaics & Renewable Energy Engineering Faculty of Engineering UNSW. "PECVD silicon nitride for n-type silicon solar cells." Publisher:University of New South Wales. Photovoltaics & Renewable Energy Engineering, 2008. http://handle.unsw.edu.au/1959.4/41277.
Full textAbstract:
The cost of crystalline silicon solar cells must be reduced in order for photovoltaics to be widely accepted as an economically viable means of electricity generation and be used on a larger scale across the world. There are several ways to achieve cost reduction, such as using thinner silicon substrates, lowering the thermal budget of the processes, and improving the efficiency of solar cells. This thesis examines the use of plasma enhanced chemical vapour deposited silicon nitride to address the criteria of cost reduction for n-type crystalline silicon solar cells. It focuses on the surface passivation quality of silicon nitride on n-type silicon, and injection-level dependent lifetime data is used extensively in this thesis to evaluate the surface passivation quality of the silicon nitride films. The thesis covers several aspects, spanning from characterisation and modelling, to process development, to device integration. The thesis begins with a review on the advantages of using n-type silicon for solar cells applications, with some recent efficiency results on n-type silicon solar cells and a review on various interdigitated backside contact structures, and key results of surface passivation for n-type silicon solar cells. It then presents an analysis of the influence of various parasitic effects on lifetime data, highlighting how these parasitic effects could affect the results of experiments that use lifetime data extensively. A plasma enhanced chemical vapour deposition process for depositing silicon nitride films is developed to passivate both diffused and non-diffused surfaces for n-type silicon solar cells application. Photoluminescence imaging, lifetime measurements, and optical microscopy are used to assess the quality of the silicon nitride films. An open circuit voltage of 719 mV is measured on an n-type, 1 Ω.cm, FZ, voltage test structure that has direct passivation by silicon nitride. Dark saturation current densities of 5 to 15 fA/cm2 are achieved on SiN-passivated boron emitters that have sheet resistances ranging from 60 to 240 Ω/□ after thermal annealing. Using the process developed, a more profound study on surface passivation by silicon nitride is conducted, where the relationship between the surface passivation quality and the film composition is investigated. It is demonstrated that the silicon-nitrogen bond density is an important parameter to achieve good surface pas-sivation and thermal stability. With the developed process and deeper understanding on the surface passivation of silicon nitride, attempts of integrating the process into the fab-rication of all-SiN passivated n-type IBC solar cells and laser doped n-type IBC solar cells are presented. Some of the limitations, inter-relationships, requirements, and challenges of novel integration of SiN into these solar cell devices are identified. Finally, a novel metallisation scheme that takes advantages of the different etching and electroless plating properties of different PECVD SiN films is described, and a preliminary evalua-tion is presented. This metallisation scheme increases the metal finger width without increasing the metal contact area with the underlying silicon, and also enables optimal distance between point contacts for point contact solar cells. It is concluded in this thesis that plasma enhanced chemical vapour deposited silicon nitride is well-suited for n-type silicon solar cells.
24
Gandhi, Keyur. "Enhancement of light coupling to solar cells using plasmonic structures." Thesis, University of Surrey, 2015. http://epubs.surrey.ac.uk/808845/.
Full textAbstract:
Photovoltaic technologies are likely to become one of the world’s major renewable energy generators in the future provided they are able to meet the increasing world energy demands at a significantly lower generation cost compared to conventional non-renewable energy sources. Photovoltaic systems based on 1st generation mono or poly crystalline silicon wafers have already been commercially successful over the past two decades. As the technology further develops however, it faces fundamental limits to further reduce cost which are primarily due to processing of silicon wafers. Hence, a 2nd generation of “thin film” photovoltaic systems, such as amorphous and poly silicon, CdTe and CIGS, which use cheap materials and inexpensive manufacturing processes with relatively high power conversion efficiency, have been developed. In order to commercialise the 2nd generation technology successfully, the efficiency of the thin film photovoltaic panels needs to increase to compete with the 1st generation silicon photovoltaics. Plasmonic structures provide a route to increase the efficiency of 2nd generation thin film photovoltaic devices. With the unique properties of plasmonic structures, such as ability to guide and trap light at nanometre dimensions, light absorption in the photoactive layer of thin film photovoltaic device can be increased resulting in improved device performance. In this research, plasmonic nanoparticles are utilised as an anti-reflection coating on the front side of the PV, coupling light into the active PV layer, and as scattering centres at the back reflector, increasing the path length of the light through the photoactive layer. The optical and electrical effects of the plasmonic structures are modelled simultaneously using a commercial technology computer aided design (TCAD) simulation package to understand and optimise the plasmonic effects on the performance of the 2nd generation thin film amorphous silicon, and 3rd generation organic, photovoltaic devices. The thesis describes the first ever dedicated optoelectronic model to simultaneously simulate optical and electrical properties of plasmonic thin film photovoltaics devices in collaboration with the TCAD software developer Silvaco Inc. The model demonstrates a maximum 12% relative increase in the power conversion efficiency of plasmon enhanced n-i-p configured amorphous silicon thin film photovoltaic devices. This remarkable increase in the performance is due to the light trapping in the photoactive layer of the thin film amorphous silicon photovoltaic devices, which results in improvements in the both the optical and electrical properties. Experimental work was also carried out to observe the plasmonic effects of the metal nanoparticles on the performance of 3rd generation organic photovoltaic devices which were subsequently modelled using the simulation package. A 4% relative increase in the efficiency was achieved using gold nanoparticles. A plasmonic organic photovoltaic device model and material library for the commercial organic semiconductor P3HT:PCBM, has also been developed and benchmarked experimentally. The model has assisted in the understanding of the effect of the plasmonic gold nanoparticles on the increased performance, as well as degradation effects due to the incorporation of silver nanoparticles.
25
Sesuraj, Rufina. "Plasmonic mirror for light-trapping in thin film solar cells." Thesis, University of Southampton, 2014. https://eprints.soton.ac.uk/366663/.
Full textAbstract:
Microcrystalline silicon solar cells require an enhanced absorption of photons in the near-bandgap region between 700-1150nm. Conventional textured mirrors scatter light and increase the path length of photons in the absorber by total internal reflection. However, these mirrors exhibit a high surface roughness which degrades the performance of the microcrystalline silicon device. An alternative solution is to use metal nanoparticles with low surface roughness to scatter light. An illuminated metal nanoparticle exhibits a resonant or plasmonic excitation which can be tuned to enable a strong scattering of light. This work aims to develop an efficient near-infrared light-scattering system using randomly arranged metal nanoparticles near a mirror. Situating the nanoparticles at the rear of the solar cell helps to target weakly absorbed photons and eliminate out-coupling losses by the inclusion of a rear mirror. Simulation results show that the electric field driving the plasmonic resonance can be tuned with particle-mirror separation distance. The plasmonic scattering is maximised when the peak of the driving field intensity coincides with the intrinsic resonance of the nanoparticle. An e-beam lithography process was developed to fabricate a pseudo-random array of Ag nanodiscs near a Ag mirror. The optimized plasmonic mirror, with 6% coverage of 200nm Ag discs, shows higher diffusive reflectivity than a conventional textured mirror in the near-infrared region, over a broad angular range. Unlike a mirror with self-organised Ag islands, the mirror with Ag nanodiscs exhibits a low surface roughness of 13.5nm and low broadband absorption losses of around 10%. An 8.20% efficient thin n-i-p μc-Si:H solar cell, with the plasmonic mirror integrated at the rear, has been successfully fabricated. The optimised plasmonic solar cell showed an increase of 2.3mA in the short-circuit current density (Jsc), 6mV in the open-circuit voltage (Voc) and 0.97% in the efficiency (η), when compared to the planar cell counterpart with no nanodiscs. The low surface roughness of the plasmonic mirror ensures no degradation in the electrical quality of the μc-Si:H layer – this is also confirmed by the constant value of the fill factor (FF). The increase in Jsc is demonstrated to be mainly due to optical absorption enhancement in the near-infrared region as a result of plasmonic scattering, by detailed calculation of the exact photogenerated current in the plasmonic and planar devices, for the 700-1150nm wavelength range.
26
Ebenhoch, Bernd. "Organic solar cells : novel materials, charge transport and plasmonic studies." Thesis, University of St Andrews, 2015. http://hdl.handle.net/10023/7814.
Full textAbstract:
Organic solar cells have great potential for cost-effective and large area electricity production, but their applicability is limited by the relatively low efficiency. In this dissertation I report investigations of novel materials and the underlying principles of organic solar cells, carried out at the University of St Andrews between 2011 and 2015. Key results of this investigation: • The charge carrier mobility of organic semiconductors in the active layer of polymer solar cells has a rather small influence on the power conversion efficiency. Cooling solar cells of the polymer:fullerene blend PTB7:PC₇₁BM from room temperature to 77 K decreased the hole mobility by a factor of thousand but the device efficiency only halved. • Subphthalocyanine molecules, which are commonly used as electron donor materials in vacuum-deposited active layers of organic solar cells, can, by a slight structural modification, also be used as efficient electron acceptor materials in solution-deposited active layers. Additionally these acceptors offer, compared to standard fullerene acceptors,advantages of a stronger light absorption at the peak of the solar spectrum. • A low band-gap polymer donor material requires a careful selection of the acceptor material in order to achieve efficient charge separation and a maximum open circuit voltage. • Metal structures in nanometer-size can efficiently enhance the electric field and light absorption in organic semiconductors by plasmonic resonance. The fluorescence of a P3HT polymer film above silver nanowires, separated by PEDOT:PSS, increased by factor of two. This could be clearly assigned to an enhanced absorption as the radiative transition of P3HT was identical beside the nanowires. • The use of a processing additive in the casting solution for the active layer of organic solar cells of PTB7:PC₇₁BM strongly influences the morphology, which leads not only to an optimum of charge separation but also to optimal charge collection.
27
Madhavan, Atul. "Alternative designs for nanocrystalline silicon solar cells." [Ames, Iowa : Iowa State University], 2009. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3403005.
Full text
28
Nordmark, Heidi. "Microstructure studies of silicon for solar cells." Doctoral thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for fysikk, 2009. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-5384.
Full text
29
Reuter, Michael [Verfasser]. "Thin Crystalline Silicon Solar Cells / Michael Reuter." München : Verlag Dr. Hut, 2011. http://d-nb.info/1012432041/34.
Full text
30
Inns, Daniel Photovoltaics & Renewable Energy Engineering Faculty of Engineering UNSW. "ALICIA polycrystalline silicon thin-film solar cells." Publisher:University of New South Wales. Photovoltaics & Renewable Energy Engineering, 2007. http://handle.unsw.edu.au/1959.4/43600.
Full textAbstract:
Thin-film silicon photovoltaics are seen as a good possibility for reducing the cost of solar electricity. The focus of this thesis is the ALICIA cell, a thin-film polycrystalline silicon solar cell made on a glass superstrate. The name ALICIA comes from the fabrication steps - ALuminium Induced Crystallisation, Ion Assisted deposition. The concept is to form a high-quality crystalline silicon layer on glass by Aluminium Induced Crystallisation (AIC). This is then the template from which to epitaxially grow the solar cell structure by Ion Assisted Deposition (IAD). IAD allows high-rate silicon epitaxy at low temperatures compatible with glass. In thin-film solar cells, light trapping is critical to increase the absorption of the solar spectrum. ALICIA cells have been fabricated on textured glass sheets, increasing light absorption due to their anti-reflection nature and light trapping properties. A 1.8 μm thick textured ALICIA cell absorbs 55% of the AM1.5G spectrum without a back-surface reflector, or 76% with an optimal reflector. Experimentally, Pigmented Diffuse Reflectors (PDRs) have been shown to be the best reflector. These highly reflective and optically diffuse materials increase the light-trapping potential and hence the short-circuit currents of ALICIA cells. In textured cells, the current increased by almost 30% compared to using a simple aluminium reflector. Current densities up to 13.7 mA/cm2 were achieved by application of a PDR to the best ALICIA cells. The electronic quality of the absorber layer of ALICIA cells is strongly determined by the epitaxy process. Very high-rate epitaxial growth decreases the crystalline quality of the epitaxial layer, but nevertheless increases the short-circuit current density of the solar cells. This indicates that the diffusion length in the absorber layer of the ALICIA cell is primarily limited by contamination, not crystal quality. Further gains in current density can therefore be achieved by increasing the deposition rate of the absorber layer, or by improving the vacuum quality. Large-area ALICIA cells were then fabricated, and series resistance reduced by using an interdigitated metallisation scheme. The best measured efficiency was 2.65%, with considerable efficiency gains still possible from optimisation of the epitaxial growth and metallisation processes.
31
Stüwe, David [Verfasser], and Jan G. [Akademischer Betreuer] Korvink. "Inkjet processes for crystalline silicon solar cells." Freiburg : Universität, 2015. http://d-nb.info/1122646984/34.
Full text
32
Shariff, A. "Computer simulation of amorphous silicon solar cells." Thesis, Swansea University, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.638814.
Full textAbstract:
A detailed numerical model of the electronic properties of hydrogenated amorphous silicon has been developed and shown to be a useful tool for the analysis of the performance and optimization of the design of solar cells. The method of simulation involves solving Poissons's equation, and the electron and hole continuity equations, in conjunction with the transport equations for the electrons and holes. From the solutions of these equations we obtained the electrostatic potential, the electron and hole concentrations and the current densities. A set of realistic material parameters has been used. We have modelled the density of states to consist of two exponential band tails and the dangling bonds. Recombination in both the band tails and the dangling bonds has been taken into consideration in the model. We investigated the effect of the cell performance on varying dangling bond densities (1016cm-3-1017cm-3) for various cell thicknesses of p-i-n hydrogenated amorphous silicon solar cells, for incident blue and red light. Our results agree well with experiments for solar cells in the undegraded state. However for the degraded state the fill factors appear to be higher than the experimental values. This might be because we have only assumed a single level dangling bond density in our model. It is suggested that future work might undertake the incorporation of the spatial dependence of the dangling bond density in the model.
33
Kaminski, Piotr M. "Remote plasma sputtering for silicon solar cells." Thesis, Loughborough University, 2013. https://dspace.lboro.ac.uk/2134/13058.
Full textAbstract:
The global energy market is continuously changing due to changes in demand and fuel availability. Amongst the technologies considered as capable of fulfilling these future energy requirements, Photovoltaics (PV) are one of the most promising. Currently the majority of the PV market is fulfilled by crystalline Silicon (c-Si) solar cell technology, the so called 1st generation PV. Although c-Si technology is well established there is still a lot to be done to fully exploit its potential. The cost of the devices, and their efficiencies, must be improved to allow PV to become the energy source of the future. The surface of the c-Si device is one of the most important parts of the solar cell as the surface defines the electrical and the optical properties of the device. The surface is responsible for light reflection and charge carrier recombination. The standard surface finish is a thin film layer of silicon nitride deposited by Plasma Enhanced Chemical Vapour Deposition (PECVD). In this thesis an alternative technique of coating preparation is presented. The HiTUS sputtering tool, utilising a remote plasma source, was used to deposit the surface coating. The remote plasma source is unique for solar cells application. Sputtering is a versatile process allowing growth of different films by simply changing the target and/or the deposition atmosphere. Apart from silicon nitride, alternative materials to it were also investigated including: aluminium nitride (this was the first use of the material in solar cells) silicon carbide, and silicon carbonitride. All the materials were successfully used to prepare solar cells apart from the silicon carbide, which was not used due to too high a refractive index. Screen printed solar cells with a silicon nitride coating deposited in HiTUS were prepared with an efficiency of 15.14%. The coating was deposited without the use of silane, a hazardous precursor used in the PECVD process, and without substrate heating. The elimination of both offers potential processing advantages. By applying substrate heating it was found possible to improve the surface passivation and thus improve the spectral response of the solar cell for short wavelengths. These results show that HiTUS can deposit good quality ARC for silicon solar cells. It offers optical improvement of the ARC s properties, compared to an industrial standard, by using the DL-ARC high/low refractive index coating. This coating, unlike the silicon nitride silica stack, is applicable to encapsulated cells. The surface passivation levels obtained allowed a good blue current response.
34
Tsuda, Shinya. "TOWARDS HIGH EFFICIENCY AMORPHOUS SILICON SOLAR CELLS." Kyoto University, 1988. http://hdl.handle.net/2433/162221.
Full text
35
Davidson, Lauren Michel. "Strategies for high efficiency silicon solar cells." Thesis, University of Iowa, 2017. https://ir.uiowa.edu/etd/5452.
Full textAbstract:
The fabrication of low cost, high efficiency solar cells is imperative in competing with existing energy technologies. Many research groups have explored using III-V materials and thin-film technologies to create high efficiency cells; however, the materials and manufacturing processes are very costly as compared to monocrystalline silicon (Si) solar cells. Since commercial Si solar cells typically have efficiencies in the range of 17-19%, techniques such as surface texturing, depositing a surface-passivating film, and creating multi-junction Si cells are used to improve the efficiency without significantly increasing the manufacturing costs. This research focused on two of these techniques: (1) a tandem junction solar cell comprised of a thin-film perovskite top cell and a wafer-based Si bottom cell, and (2) Si solar cells with single- and double-layer silicon nitride (SiNx) anti-reflection coatings (ARC).
The perovskite/Si tandem junction cell was modeled using a Matlab analytical program. The model took in material properties such as doping concentrations, diffusion coefficients, and band gap energy and calculated the photocurrents, voltages, and efficiencies of the cells individually and in the tandem configuration. A planar Si bottom cell, a cell with a SiNx coating, or a nanostructured black silicon (bSi) cell can be modeled in either an n-terminal or series-connected configuration with the perovskite top cell. By optimizing the bottom and top cell parameters, a tandem cell with an efficiency of 31.78% was reached.
Next, planar Si solar cells were fabricated, and the effects of single- and double-layer SiNx films deposited on the cells were explored. Silicon nitride was sputtered onto planar Si samples, and the refractive index and thicknesses of the films were measured using ellipsometry. A range of refractive indices can be reached by adjusting the gas flow rate ratios of nitrogen (N2) and argon (Ar) in the system. The refractive index and thickness of the film affect where the minimum of the reflection curve is located. For Si, the optimum refractive index of a single-layer passivation film is 1.85 with a thickness of 80nm so that the minimum reflection is at 600nm, which is where the photon flux is maximized. However, using a double-layer film of SiNx, the Si solar cell performance is further improved due to surface passivation and lowered surface reflectivity. A bottom layer film with a higher refractive index passivates the Si cell and reduces surface reflectivity, while the top layer film with a smaller refractive index further reduces the surface reflectivity. The refractive indices and thicknesses of the double-layer films were varied, and current-voltage (IV) and external quantum efficiency (EQE) measurements were taken. The double-layer films resulted in an absolute value increase in efficiency of up to 1.8%.
36
Manley, Phillip [Verfasser]. "Simulation of Plasmonic Nanoparticles in Thin Film Solar Cells / Phillip Manley." Berlin : Freie Universität Berlin, 2016. http://d-nb.info/1107011779/34.
Full text
37
Wang, Chuandao Charlie, and 王传道. "Organic solar cells towards high efficiency: plasmonic effects and interface engineering." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2012. http://hub.hku.hk/bib/B48329654.
Full textAbstract:
Organic solar cells (OSCs) are promising candidates for solar light harvesting due to their standout advantages both in material properties and manufacturing process. During past decades, remarkable progress has been achieved. Efficiency for single-junction cells over 9% and tandem cells over 10% has been reported. For high performance OSCs towards commercialization, sufficient light absorption and high quality buffer layers are still two challenges, which are addressed in this thesis by investigating the plasmonic effects on OSCs and interface engineering.
Here, the mechanisms of plasmonic effects on OSC are explored by incorporating metallic Au nanoparticles (NPs) in individual anode buffer layer and active layer, respectively, and finally in both layers simultaneously. When Au NPs are incorporated into the buffer layer, surface plasmonic resonance (SPR) induced absorption enhancement due to incorporation of Au NPs is evidenced theoretically and experimentally to be only minor contributor to the performance improvement. The increased interfacial contact area between the buffer layer and active layer, together with the reduced resistance of the buffer layer due to the embedded Au NPs, are revealed to benefit hole collection and thus are main contributors to the performance improvement. When Au NPs are embedded in the active layer, Au NPs induced SPR indeed contributes to enhanced light absorption. However, when large amount of Au NPs are incorporated, the negative effects of NPs on the electrical properties of OSCs can counter-diminish the optical enhancement from SPR, which limits the overall performance improvement. When Au NPs are embedded into both layers, both advantages of incorporating NPs in individual layers can be utilized together to achieve more pronounced improvement in photovoltaic performance; as a result, accumulated enhancements in device performance can be achieved. The results herein are applicable to other metallic NPs such as Ag NPs, Pt NPs, etc. The study herein has clarified the degree of contribution of SPR effects on OSCs and revealed the mechanisms behind. It has also highlighted the importance of considering both optical and electrical effects when employing metallic NPs as strategies to enhance the photovoltaic performance of OSCs. Consequently, the study contributes both physical understanding and technological development of applying metallic NPs on OSCs.
Regarding interface engineering, we first propose a simple method to modify the substrate work function for efficient hole collection by using an ultra-thin ultraviolet-ozone treated Au. The method can be used in other situations such as modifying the work function of multilayer graphene as transparent electrode. Then we propose a general method to synthesize solution-processed transition metal oxides (TMOs). Besides high material quality, desirable electrical properties, and good stability, our method stands out particular in that the synthesized TMOs can be dispersed in water-free solvents and the TMO films require only low temperature treatment, which is very compatible with the organic electronics. Our method can also be used to synthesize other TMOs other than the demonstrated molybdenum oxide and vanadium oxide. The proposed method herein is applicable in semiconductor industry.published_or_final_version
Electrical and Electronic Engineering
Doctoral
Doctor of Philosophy
38
Lu, Meijun. "Silicon heterojunction solar cell and crystallization of amorphous silicon." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file, 295 p, 2009. http://proquest.umi.com/pqdweb?did=1654494651&sid=3&Fmt=2&clientId=8331&RQT=309&VName=PQD.
Full text
39
Demircioglu, Olgu. "Optimization Of Metalization In Crystalline Silicon Solar Cells." Master's thesis, METU, 2012. http://etd.lib.metu.edu.tr/upload/12614584/index.pdf.
Full textAbstract:
iv
ABSTRACT
OPTIMIZATION OF METALIZATION IN
CRYSTALLINE SILICON SOLAR CELLS
Demircioglu, Olgu
M. Sc. Department of Micro and Nanotechnology
Supervisor : Prof. Dr. Rasit Turan
Co-Supervisor : Assist. Prof. Dr. H. Emrah Ünalan August 2012, 103 pages Production steps of crystalline silicon solar cells include several physical and chemical processes like etching, doping, annealing, nitride coating, metallization and firing of the metal contacts. Among these processes, the metallization plays a crucial role in the energy conversion performance of the cell. The quality of the metal layers used on the back and the front surface of the cell and the quality of the electrical contact they form with the underlying substrate have a detrimental effect on the amount of the power generated by the cell. All aspects of the metal layer, such as electrical resistivity, contact resistance, thickness, height and width of the finger layers need to be optimized very carefully for a successful solar cell operation. In this thesis, metallization steps within the crystalline silicon solar cell production were studied in the laboratories of Center for Solar Energy Research and Application (GÜ
NAM). Screen Printing method, which is the most common metallization technique in the industry, was used for the metal layer formation. With the exception of the initial experiments, 6
40
Macdonald, Daniel Harold, and daniel@faceng anu edu au. "Recombination and Trapping in Multicrystalline Silicon Solar Cells." The Australian National University. Faculty of Engineering and Information Technology, 2001. http://thesis.anu.edu.au./public/adt-ANU20011218.134830.
Full textAbstract:
In broad terms, this thesis is concerned with the measurement and interpretation of carrier lifetimes in multicrystalline silicon. An understanding of these lifetimes in turn leads to a clearer picture of the limiting mechanisms in solar cells made with this promising material, and points to possible paths for improvement. The work falls into three broad categories: gettering, trapping and recombination. A further section discusses a powerful new technique for characterising impurities in semiconductors in general, and provides an example of its application.
Gettering of recombination centres in multicrystalline silicon wafers improves the bulk lifetime, often considerably. Although not employed deliberately in most commercial cell processes, gettering nevertheless occurs to some extent during emitter formation, and so may have an important impact on cell performance. However, the response of different wafers to gettering is quite variable, and in some cases is non-existent. Work in this thesis shows that the response to gettering is best when the dislocation density is low and the density of mobile impurities is high. For Eurosolare material these conditions prevail at the bottom and to a lesser extent in the middle of an ingot. However, these conclusions can not always be applied to multicrystalline silicon produced by other manufacturers. Low resistivity multicrystalline silicon suffers from a concurrent thermally induced degradation of the lifetime. This had previously been attributed to the dissolution of precipitated metals, although we note that the crystallographic quality also appears to deteriorate. The thermal degradation effect results in an optimum gettering time for low resistivity material. Edge-defined Film-fed Growth (EFG) ribbon silicon was also found to respond to gettering, and even more so to bulk hydrogenation. Evidence for Cu contamination in the as-grown EFG wafers is presented.
Multicrystalline silicon is often plagued by trapping effects, which can make lifetime measurement in the injection-level range of interest very difficult, and sometimes impossible. An old model based on centres that trap and release minority carriers, but do not interact with majority carriers, was found to provide a good explanation for these effects. These trapping states were linked with the presence of dislocations and also with boron-impurity complexes. Their annealing behaviour and lack of impact on device parameters can be explained in terms of the models developed. The trapping model allowed a recently proposed method for correcting trap-affected data to be tested using typical values of the trapping parameters. The correction method was found to extend the range of useable data to approximately an order of magnitude lower in terms of carrier density than would be available otherwise, an improvement that could prove useful in many practical cases.
High efficiency PERL and PERC cells made on gettered multicrystalline silicon resulted in devices with open circuit voltages in the 640mV range that were almost entirely limited by bulk recombination. Furthermore, the injection-level dependence of the bulk lifetime resulted in decreased fill factors. Modelling showed that these effects are even more pronounced for cells dominated by interstitial iron recombination centres. Analysis of a commercial multicrystalline cell fabrication process revealed that recombination in the emitter created the most stringent limit on the open circuit voltage, followed by the bulk and the rear surface. The fill factors of these commercial cells were mostly affected by series resistance, although some reduction due to injection-level dependent lifetimes seems likely also. Secondary Ion Mass Spectroscopy on gettered layers of multicrystalline silicon revealed the presence of Cr and Fe in considerable quantities. Further evidence strongly implied that they resided almost exclusively as precipitates.
More generally, injection-level dependent lifetime measurements offer the prospect of powerful contamination-monitoring tools, provided that the impurities are well characterised in terms of their energy levels and capture cross-sections. Conversely, lifetime measurements can assist with this process of characterising impurities, since they are extremely sensitive to their presence. This possibility is explored in this thesis, and a new technique, dubbed Injection-level Dependent Lifetime Spectroscopy (IDLS) is developed. To test its potential, the method was applied to the well-known case of FeB pairs in boron-doped silicon. The results indicate that the technique can offer much greater accuracy than more conventional DLTS methods, and may find applications in microelectronics as well as photovoltaics.
41
Yao, Guoxiao Centre for Photovoltaic Engineering UNSW. "High efficiency metal stencil printed silicon solar cells." Awarded by:University of New South Wales. Centre for Photovoltaic Engineering, 2005. http://handle.unsw.edu.au/1959.4/23062.
Full textAbstract:
This thesis work demonstrates the feasibility to fabricate high-efficiency crystalline silicon solar cells by using metal stencil printing technique to replace screen printing or electroless plating techniques for implementing crystalline silicon solar cell front metallization. The developed laser-cut stainless steel stencils successfully challenge two of the cell performance limitations associated with commercial screen printing technology: the wide and non-uniform front gridline fingers and low height-to-width aspect ratio of the fingers. These limitations lower the short circuit current density, the fill factor and, in turn, the efficiency of a screen printed solar cell. Metal stencils are capable of printing fine, high and continuous features on the cell front that have a high aspect ratio. Both single-level and double-level structured stainless steel stencils for solar cell front metallization have been developed, with laser-cut double-level stainless steel stencils being demonstrated for the first time worldwide. Both of them are able to print fine, high and continuous gridline pattern to the front surfaces of solar cells in one step, with a certain number of special short bridges being put at the places where fingers meet busbar and along fingers and busbar. The deformation issue of the very thin stainless steel foils due to its thermal expansion in the process of laser cutting is solved by increasing the energy content in each laser pulse that impinges upon the stainless steel foil with changed Q-switch frequencies, while maintaining the laser average output energy in unit time to an optimum value. A chemical etching process has been developed to etch the dross that results from laser cutting, resulting in well formed metal stencils suitable for printing. By a comparison between the metal stencil printed and conventional mesh screen printed silicon solar cells, which are fabricated on similar Cz silicon wafers with a almost identical cell processing sequence except for using different front contact printing masks, the following conclusions are reached: Fired Ag finger lines with 75-??m width on finished solar cells, using a doublelevel stainless steel stencil can be achieved. In contrast, the fired Ag finger line on finished solar cells using a traditional mesh screen is 121-??m wide. The stencil printed finger is smoother and more uniform than by screen printing and the former has a 25-??m fired finger height with a 0.33 height-to-width aspect ratio, compared to a 10-??m fired finger height with a 0.08 height-to-width aspect ratio for the later. With these advantages, the 4-cm2 stencil-printed silicon solar cells has an averaged 1.28 mA/cm2 higher short circuit current and an averaged 5.9% higher efficiency than the 4-cm2 screen printed silicon solar cell, which identifies one of the key advantages of solar cell metallization schemes by using metal stencil printing in place of screen printing. Using a ???feedback alignment??? method for registration of the laser-formed metal stencil printed pattern and the laser-formed groove pattern, Ag paste can be printed and filled into wafer grooves by using a hand-operated without an optical vision system. The fired finger profile is 50-??m wide and 22-??m high. The best metal stencil printed, selective emitter silicon solar cell demonstrates a 34.2 mA/cm2 short circuit current density, 625 mV open circuit voltage, 0.77 fill factor and 16.4% efficiency, with an excellent spectral response at short wavelengths due to its selective emitter cell structure. It is believed that the performance of this type of solar cell can be enhanced with a screen printer that has an optical vision system and an automatic alignment device. The successful development of metal stencil printed silicon solar cells demonstrates the feasibility of the metal stencil printing as a beneficial technology for the PV industry.
42
Song, Yang Photovoltaics & Renewable Energy Engineering Faculty of Engineering UNSW. "Dielectric thin film applications for silicon solar cells." Publisher:University of New South Wales. Photovoltaics & Renewable Energy Engineering, 2009. http://handle.unsw.edu.au/1959.4/44486.
Full textAbstract:
Dielectric thin films have a long history in silicon photovoltaics. Due to the specific physical properties, they can function as passivation layer in solar cells. Also, they can be used as antireflection coating layers on top of the devices. They can improve the back surface reflectance if proper dielectric layers combination is used. What??s more, they can protect areas by masking during chemical etching, diffusion, metallization among the whole fabrication process. Crystalline silicon solar cell can be passivated by two ways: one is to deposit dielectric thin films to saturate the dangling bonds; the other is to introduce surface electrical field and repel back the minority carriers. This thesis explores thermally grown SiO2 and sputtered Si3N4(:H) to passivate n-type and thermal evaporation AlF3 to passivate p-type Float Zone silicon wafers, respectively. Sputtering is a cheap passivation method to replace PECVD in industry usage, but all sputtered samples are more likely to have encountered surface damage from neutral Ar and secondary electrons, both coming from the sputtered target. AlF3/SiO2 multi-layer stack is a negative charge combination; p inversion layer will form on the wafer surface. Light trapping is an important part in solar cell research work. In order to enhance the reflectance and improve the absorption possibility of near infrared photons, especially for high efficiency PERL cell application, the back surface structure is optimized in this work. Results show SiO2/Ag is a very good choice to replace SiO2/Al back reflectors. The maximum back surface reflectance is 97.82%. At the same time, SiO2/Ag has excellent internal angle dependence of reflectance, which is beneficial for surface textured cells. A ZnS/MgF2/SiO2/Al(Ag) superlattice can improve the back reflectance, but it is sensitive to incident angle inside the silicon wafer. If planar wafers are used to investigate all kinds of back reflectors, and an 8 degrees incident angle is fixed for typical spectrometry measurement, the results are easy to predict by Wvase software simulation. If a textured surface is considered, the light path inside the silicon wafer is very complicated and hard to calculate and simulate. The best way to evaluate the result is through experiment.
43
Liang, Jianjun. "Device physics of hydrogenated amorphous silicon solar cells." Related electronic resource: Current Research at SU : database of SU dissertations, recent titles available full text, 2006. http://proquest.umi.com/login?COPT=REJTPTU0NWQmSU5UPTAmVkVSPTI=&clientId=3739.
Full text
44
Jamshidi, Gohari Ebrahim. "Buried screen-printed contacts for silicon solar cells." Thesis, Högskolan Dalarna, Energi och miljöteknik, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:du-13593.
Full textAbstract:
A Simple way to improve solar cell efficiency is to enhance the absorption of light and reduce the shading losses. One of the main objectives for the photovoltaic roadmap is the reduction of metalized area on the front side of solar cell by fin lines. Industrial solar cell production uses screen-printing of metal pastes with a limit in line width of 70-80 μm. This paper will show a combination of the technique of laser grooved buried contact (LGBC) and Screen-printing is able to improve in fine lines and higher aspect ratio. Laser grooving is a technique to bury the contact into the surface of silicon wafer. Metallization is normally done with electroless or electrolytic plating method, which a high cost. To decrease the relative cost, more complex manufacturing process was needed, therefore in this project the standard process of buried contact solar cells has been optimized in order to gain a laser grooved buried contact solar cell concept with less processing steps. The laser scribing process is set at the first step on raw mono-crystalline silicon wafer. And then the texturing etch; phosphorus diffusion and SiNx passivation process was needed once. While simultaneously optimizing the laser scribing process did to get better results on screen-printing process with fewer difficulties to fill the laser groove. This project has been done to make the whole production of buried contact solar cell with fewer steps and could present a cost effective opportunity to solar cell industries.In collaboration with Institute for Photovoltaics IPV, University of Stuttgart.
45
Heß, Uwe [Verfasser]. "Investigations of RGS Silicon Solar Cells / Uwe Heß." München : Verlag Dr. Hut, 2013. http://d-nb.info/1037286839/34.
Full text
46
Shih, Jeanne-Louise. "Zinc oxide-silicon heterojunction solar cells by sputtering." Thesis, McGill University, 2007. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=112583.
Full textAbstract:
Heterojunctions of n-ZnO/p-Si solar cells were fabricated by RF sputtering ZnO:Al onto boron-doped (100) silicon (Si) substrates. Zinc Oxide (ZnO) films were also deposited onto soda lime glass for electrical measurements. Sheet resistance measurements were performed with a four-point-probe on the glass samples. Values for samples evacuated for 14 hours prior to deposition increased from 7.9 to 10.17 and 11.5 O/□ for 40 W, 120 and 160 W in RF power respectively. In contrast, those evacuated for 2 hours started with a higher value of 22.5 O/□, and decreased down to 7.6 and 5.8 O/□. Vacuum annealing was performed for both the glass and the Si samples. Current-voltage measurements were performed on the ZnO/Si junctions in the dark and under illumination. Parameters such as open-circuit voltage, Voc; short-circuit current, Isc; fill factor, FF; and efficiency, eta were determined. A maximum efficiency of 0.25% among all samples was produced, with an I sc of 2.16 mA, Voc of 0.31V and a FF of 0.37. This was a sample fabricated at an RF power of 80 W. Efficiency was found to decline with vacuum annealing. Furthermore, interfacial state density calculated based on capacitance-voltage measurements showed an increase in the value with vacuum annealing. The results found suggest that the interface states may be due to an interdiffusion of atoms, possibly those of Zn into the Si surface. The Electron Beam Induced Current (EBIC) method was used to determine diffusion length to be at a value ∼40--80 mum and therefore a minority carrier lifetime calculated of 3 musec. It was also used to determine the surface recombination velocity (SRV) of the fractured surface of the Si bulk from the fabricated solar cells. An SRV of ∼500 cm/sec was determined from the fractured Si surface, at a point located at 30 and 20 mum away from the junction interface.
47
Tucher, Nico [Verfasser], Claas [Verfasser] Müller, and Stefan [Verfasser] Glunz. "Analysis of photonic structures for silicon solar cells." Freiburg : Universität, 2016. http://d-nb.info/1136567186/34.
Full text
48
Lu, Chien Ming, and 盧建明. "Efficiency improvement of silicon solar cells using plasmonic nanoparticles." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/ke3gyf.
Full textAbstract:
碩士長庚大學
光電工程研究所
105
In this study,dilute nano-silver solution was coating on the surface of silicon solar cells that its surface plasmonic structure can prompt the absorption of the solar cell, thereby enhancing the correspondent efficiency. In the first part, the correspondent concentration of diluted nano-silver solutions 10%, 20%, 30% and 40% are coated on the anti-reflective layer of each silicon solar cell which has a size of 2x 2 mm2 . The second part is coated with the toluene liquid and annealed. The third part of this thesis is the large-scale, 156 x 156 mm2, solar cells coated with nano-silver. All for the efficiency enhancement of the different conditions’ nanopartcles coated silicon solar cells.The surface distribution of nano-silver was observed by the field emission scanning electron microscopy (FE-SEM), and various characteristics of the solar cell were studied by using the current-voltage curve measurement on the solar cell simulator. Further, the ultraviolet / visible- Spectroscopy (UV / VIS) was used to investigate the coated layers’ optical properties.
49
Ho, Chung-I., and 何宗一. "Three-dimensional nanorods and plasmonic nanoparticles thin film hydrogenated amorphous silicon solar cells." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/97265275147775225651.
Full textAbstract:
博士國立臺灣大學
光電工程學研究所
101
This thesis explores various types of nanostructures in single junction hydrogenated amorphous silicon (a-Si:H) solar cells. The nanometer-sized structures are promising due to their excellent optical and electronic properties. They provide an effective way to increase optical path length inside solar cell, and thus result in improved energy conversion efficiency. This thesis is divided into two primary tasks: plasmonic nanoparticles and three-dimensional nanorods structures. First, the plasmonic-structure incorporated multilayer of Au nanoparticles embedded in the transparent conducting oxide at the back reflector of a-Si:H solar cells is demonstrated. The effect of the nanoparticles density and the number of multilayer of the nanoparticles in tuning the plasmon resonances for better scattering are investigated by measuring optical characteristics. The double-layer Au nanoparticles structure has an advantage over single-layer for harvesting light. In addition to enhanced light scattering, applying high-work-function Au nanoparticles can improve the matching of work function at TCO/a-Si:H interface. Second, the a-Si:H solar cells based on three-dimensional ZnO nanorods arrays prepared by hydrothermal growth is demonstrated. The influence of the absorber layer thickness and rod length on the performance of a-Si:H solar cells are investigated in detail. Focus in on the concept of applying three-dimensional nanorods for electronically thin and optically thick in achieving high efficiency a-Si:H solar cells. Third, the a-Si:H solar cells based on random textures substrates incorporating ZnO nanorod arrays is demonstrated. Highly-oriented ZnO nanorods are grown on textured substrate (Asahi-U glass) through hydrothermal growth. It is found that the surface morphology and diffuse scattering property are strongly dependent on the concentration of reagents. By controlling the experimental conditions, the flower-like ZnO nanostructure is successfully obtained. Fourth, in terms of previous tasks, plasmonic Au nanoparticles and three-dimensional nanorod arrays are combined to demonstrate a new type of nanoparticles decorated nanorods a-Si:H solar cell. The ultra-thin Au film are deposited on the surface of nanorods by thermal evaporation system to form Au nanoparticles. The scattering property between plasmonic nanoparticles and three-dimensional nanorods are investigated systematically. By optimizing thickness of Au metal film appropriately, the improved energy conversion efficiency is obtained for the nanoparticles decorated nanorods a-Si:H solar cell.
50
Su, Shih-Ya, and 蘇詩雅. "Performance Characterization of Texturing Silicon Solar Cells Using Silver and Indium Nanoparticles Plasmonic Scattering." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/3u98ky.
Full textAbstract:
碩士國立臺北科技大學
光電工程系研究所
103
In this paper, the properties of silicon solar cells using the surface plasmon resonance effects generated through the embedded metal nanoparticles are investigated. First, the nanoscale metallic siliver (Ag) and indium (In) nanoparticles (NPs) were deposited on the titanium dioxide (TiO2) space layer with various thickness. Then, a layer of aluminum oxide (Al2O3) was coated on the cells with NPs, it exhibited a cell with plasmon antireflective coating (PARC) layer. The PARC layer provides both double anti-reflection and SPR effects to improve the incident photons absorbed in semiconductor as well as to enhance the photocurrent (Iph) and conversion efficiency (η), the reflectivity, external quantum efficiency (EQE), dark I-V and photovoltaic I-V characteristics of the PARC solar cell are measured and compared. The photovoltaic performance of PARC structure silicon solar cell and double layer anti-reflective coating (DL-ARC) which having a 20-nm TiO2 and a 65-nm Al2O3, were measured and compared. The short-current density enhancement (ΔJsc) of 10.16% (from 31.14 mA/cm2 to 35.05 mA/cm2) and the conversion efficiency enhancement of (Δƞ) 16.80% (from 12.50 % to 14.60%) were obtained for the cell with DL-ARC. However, theΔJsc of 12.68% (from 31.60 mA/cm2 to 34.81 mA/cm2) and Δƞ of 20.40% (from 9.48% to 15.85%) were achieved for the cell with PARC structure. In summary, an additional enhancement of light trapping was obtained for the cell with a PARC layer, compared to the cell with DL-ARC.