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1
Jons, Mattias. "Doped 3C-SiC Towards Solar Cell Applications." Thesis, Linköpings universitet, Halvledarmaterial, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-148595.
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The market for renewable energy sources, and solar cells in particular is growing year by year, as a result there is a large interest in research on new materials and new technologies for solar power applications. In this thesis the photovoltaic properties of cubic silicon carbide (3C-SiC) has been investigated. The research includes material growth using the sublimation epitaxy method, both n-type and p-type SiC have been investigated. 3C-SiC pn junctions have been produced and their electrical properties have been characterized, this is the first time 3C-SiC pn junctions have been studied in the research group. Photoresponse has been demonstrated from a 3C-SiC pn junction with Al and N used as p- and ntype dopants. This is the first demonstrated solar cell performance using 3C-SiC, to our knowledge.
2
Fyhn, Anna Maren Andersen. "Electrodeposition of Metal Oxides for Solar Cell Applications." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for fysikk, 2012. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-16361.
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This thesis investigates the electrodeposition process of zinc-, copper-, silver-, and silver copperoxides at cathodic and anodic voltages. Silver copper oxide has been successfully electrodepositedon a substrate of PtSi from a pH 12 dilute solution of copper nitrate, silver nitrate and sodiumhydroxide at 0.9V vs a silver metal cathode. This film was confirmed to be polycrystalline AgCuO2by EDS and XRD studies. Zinc oxide and copper oxide were deposited on gold substrates from their respective nitrates. The zinc oxide deposition was confirmed polycrystalline in XRD and had a band gap between 3.2eV and 3.5eV measured by optical reflectance. The copper oxide appeared polycrystalline in SEM but only amorphous signal was achieved in XRD, the material had a band gap of around 2eV. Despite many attempts, clean silver oxide was not successfully deposited. These materials may all be suitable for solar cells applications.
3
Alam, Firoz. "Fabrication and characterization of surfactant free metal chalcogenides (Pbs and SnS) for photovoltaic applications." Thesis, IIT Delhi, 2016. http://localhost:8080/xmlui/handle/12345678/7043.
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Espindola, Rodriguez Moises. "Kesterite Deposited by Spray Pyrolysis for Solar Cell Applications." Doctoral thesis, Universitat de Barcelona, 2015. http://hdl.handle.net/10803/346633.
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Solar cells generate electrical power by direct conversion of solar radiation into electricity using semiconductors. Once produced, the solar cells do not require the use of water; operate in silence and can be easily installed almost everywhere, as solar panels with low technological risk. In this thesis new photovoltaic materials and solar cells are investigated.
From the beginning of the semiconductor era, silicon has been present; the semiconductor theory improved with the silicon technology, almost taking the idealized models to reality in within silicon. In the recent years plenty of new natural and artificially produced materials have seen the light; some of them are still waiting to be understood and explained by a new theory that has to be experimentally proved right. The clue for a better and faster progress is to work in a multidisciplinary frame; as this thesis shows, all research and knowledge has to have future protections and possibilities of been used in the benefit of our society.
Today, the photovoltaic technology (PV) based on silicon solar cells dominates the market. The thin film PV such as GaAs, Cu(In,Ga)Se2 (GIGS) and CdTe have reached power conversion efficiencies above 20% which makes them industrially interesting despite the use of scare and/or very toxic elements. Researchers and investors are expectant for a new stable, eco-friendly, inexpensive, fast and easy to produce material that could be used in a big scale and long term for photovoltaic terrestrial applications.
Some years ago it was believed that this ideal material was near to be confirmed when the reflectors were on a new chalcogenide material: Cu2ZnSn(SxSe1-x)4 (CZTSSe) called kesterite after its crystal structure. This semiconductor is very attractive due to its constituent elements, semiconductor properties. Its similarity with GIGS and compatibility with the already existing industrial processes made possible its rapid power conversion efficiency rise as absorber material in thin film solar cells. Through the years kesterite has been found to be a challenging material due to the energetically feasible mixture of stannite and kesterite structures, the high probability of defects, and the narrowness of the optimum compositional region (compared with that of chalcopyrites) that eases the formation of secondary phases limiting the efficiency of the solar cells.
Recently, CZTSSe thin film solar cells with certified efficiency of 12.6% were produced by IBM; synthesized by spin-coating using a hydrazine-based pure solution approach on a soda-lime glass (SLG) Mo coated substrate. The use of hydrazine is the key for the record as well its mayor drawback however it demonstrates the robustness of the solution-based techniques.
In this thesis the use of a cool-wall vertical pneumatic spray pyrolysis system (SP) is demonstrated as a synthesis technique of CZTS kesterite thin films from water and alcohol-based precursor solutions containing metal salts and thiourea. In the course of this thesis, the possibilities and limitations of this synthesis technique and the resulting films are explored in the frame of system- and solution-related parameters.
The SP system used in this thesis is sophisticate and advantageous; is able of reproduce
the open-air conditions used in typical spray systems but also it is capable of grow films by
spraying in an oxygen-free atmospheres such as Ar or Ar-H2 or any other. It was completely new spray approach by the year of the publication of our first repot (2013) with a 0.5% efficient working solar cell. A remarkable efficiency value by the time of publication if considered the combo challenge: material + deposition technique. In this thesis, air, Ar and Ar-H2 were used as carrier gas and atmosphere, where the so sprayed films were studied in combination with other system parameters (solution flux, time of spraying, substrate temperature, etc.) and some solution related parameters (solvent, metal precursors concentration, solution stability, etc.). To obtain device grade films, the sprayed kesterite ought to be annealed; this annealing process is also subject of study in this thesis. One step annealing at high temperature (580°C) at room pressure in S-containing reactive atmosphere was optimized for the CZTS-based thin films with efficiencies of 1.4%. To synthesize CZTSSe films, different annealing approaches were tried; one step room pressure annealing (at 550°C) in Se- containing reactive atmosphere probed to be the optimum for sprayed kesterite from methanol-based precursor solutions for solar cells with the highest conversion efficiency of 1.9% obtained in this thesis. The results showed here open many new possibilities for the use of spray systems for the synthesis of PV quality materials for solar cells applications.En esta tesis se demuestra el uso de un sistema de spray pyrolysis utilizado para sintetizar kesterita de azufre puro (CZTS) un material que representa un reto tecnológico y científico en el campo de las celdas solares de películas delgadas. La síntesis de este material es llevada a cabo en un sistema de spray en atmosfera controlada en el marco de los parámetros del sistema y de la solución; evitando el uso de reactivos altamente peligrosos utilizando en su caso agua y alcoholes. Se demuestra la síntesis de materiales del tipo CZTSSe después de un proceso de selenización; las celdas solares resultantes muestran las posibilidades del material y del sistema.
5
Mavundla, Sipho Enos. "One-Dimensional nanostructured polymeric materials for solar cell applications." Thesis, University of the Western Cape, 2010. http://etd.uwc.ac.za/index.php?module=etd&action=viewtitle&id=gen8Srv25Nme4_1088_1305888911.
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This work entails the preparation of various polyanilines with different morphologies and their application in photovoltaic solar cells. Zinc oxide (ZnO) with one-dimensional and flower-like morphology was also prepared by microwave irradiation and used as electron acceptors in photovoltaics devices. The morphological, structural, spectroscopic and electrochemical characteristics of these materials were determined by scanning electron microscopy (SEM), X-Ray diffraction (XRD), Raman, Fourier-transformed infrared spectroscopy (FTIR), ultraviolet and visible spectroscopy (UV-Vis), photoluminescence(PL), thermal gravimetric analysis (TGA) and cyclic voltammetry (CV) experiments. Devices fabricated from these materials were characterized under simulated AM 1.5 at 800 mW.
6
Koulentianos, Dimitrios. "Quantum confinement effect in materials for solar cell applications." Thesis, Uppsala universitet, Materialteori, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-237189.
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Shang, Xiangjun. "Study of quantum dots on solar energy applications." Doctoral thesis, KTH, Teoretisk kemi och biologi, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-94021.
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This thesis studies p-i-n GaAs solar cells with self-assembled InAs quantum dots (QDs) inserted. The values of this work lie in three aspects. First, by comparing the cell performance with QDs in the i-region and the n-region, the photocurrent (PC) production from QDs by thermal activation and/or intermediate band (IB) absorption is proved to be much lower in efficiency than tunneling. Second, the efficiency of PC production from QDs, characterized by PC spectrum, is helpful to design QD-based photodetectors. Third, closely spaced InAs QD layers allow a strong inter-layer tunneling, leading to an effective PC production from QD deep states, potential for solar cell application. Fourth, from the temperature-dependent PC spectra the minority photohole thermal escape is found to be dominant on PC production from QDs in the n-region. The thermal activation energy reflects the potential variations formed by electron filling in QDs. Apart from InAs QDs, this thesis also explores the blinking correlation between two colloidal CdSe QDs. For QD distance of 1 µm or less, there is a bunched correlation at delay τ = 0, meaning that the two QDs blink synchronously. Such correlation disappears gradually as QD distance increases. The correlation is possibly caused by the stimulated emission between the two nearby QDs.QC 20120507
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Henriksen, Lisa Grav. "Pump-probe experiments of multicrystalline silicon for solar cell applications." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for fysikk, 2012. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-19207.
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In order to make cost effective solar cells from mc-Si materials, the negative contributions from defects and impurities should be reduced. The analysis of the photogenerated carrier properties is therefore of great importance for characterising carrier processes and hence, for improving the material performance.In this work, pump-probe measurement of a range of silicon wafers have been performed, using anultrafast laser of 800 nm wavelength and 85 fs pulses. The optical response in the samples were analysed by measuring the reflected probe beam initial transient.The purpose of this theses was to explore the use of pump-probe experiment to study carrier dynamics in mc-Si. Measurements of single c-Si samples were used as a basis for developing good experimental skills as well as achieving knowledge about carrier dynamics in c-Si. The initial Delta R/R was studied for a range of input parameters, aiming to characterise important contributions to the measurements.The effects of passivation has been studied, indicating a significant contribution to R~R. Etchingoff the passivated layer of an oxide (SiO2) wafer, showed a radically increased in pump beam reflectivity, from 9% to 32%, and a reduced DeltaR~R from 47×10-6 to 37×10-6 was be observed. Analysis has showed that incident angle may be chose such that the pump reflection loss is at a minimum for the given passivation thickness.The final results showed a R~R is in the range of (14-41)e-6 for bare c-Si, and (47-171)e-6 for passivated c-Si wafers.Ultrafast initial recovery has been observed for mc-Si samples, and attributed to trapping of carriers. Decay times in the range of 1-6 ps are deduced and trapping densities are found as (1:3 - 4:3) × 10^18 cm-3, which is in the same order as the excitation densities.A methodology for using pump-probe measurements to analyse mc-Si samples is established, and the technique is used in characterising the observed defect states, which is of great interest for improving solar cell materials.
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Ekstrøm, Kai Erik. "Growth and Characterization of Silicon Nanowires for Solar Cell Applications." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for kjemi, 2011. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-18337.
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Si-nanowires are being introduced as an attempt to decrease the high recombination rate present in silicon based thin-film solar cells by employing radial pn-junctions instead of conventional planar pn-junctions. Previous publications have also shown an additional increase in the amount of absorbed light when covering a silicon-substrate in silicon nanowires which may result in a further increase in the total efficiency of a thin-film solar cell. Successful growth of Si-nanowires has earlier been performed by Chemical Vapour Deposition (CVD), employing gold (Au) as catalytic material. Au is a very stable catalytic material for nanowire growth but Au-residues are unwanted in solar cell applications, and the current experiment has therefore investigated aluminium (Al) as an alternative catalyst material. However, stable Al-catalysed growth has been proven to be difficult and is assumed to be mainly due to rapid oxidation of Al to Al2O3. Most of the nanowires were short, tapered and consisted of worm-like structures. Several unsuccessful in-situ NH3-based cleaning (CVD) processes were attempted. Tin (Sn) was also attempted as a protective coating for the Al-film in order to protect Al from exposure to air during sample transport, without any luck. As solar cells require both p-doped and n-doped sections in order to form pn-junctions, initial investigations were performed on the effect from the addition of dopant gases (B2H6 and PH3) on nanowire morphology. The addition of B2H6 to the gas flow seemed to have much larger effects than PH3 on the nanowire morphology compared to intrinsic nanowires. Both gases resulted in a continuous reduction in the average nanowire length with increasing dopant⁄SiH4 ratios, ultimately leading to a complete inhibition of nanowire growth. The highest usable dopant⁄SiH4 ratios before complete growth-inhibition were found to ~10^-3 for B2H6 and ~10^-1 for PH3. An undesirable tapering effect was also found when adding B2H6 to the gas-flow, resulting in radial growth of amorphous silicon on the nanowire walls already at the lowest dopant ratio (~10^-5). This may complicate the use of B2H6 as a dopant gas for p-type nanowires. Ignoring the fact that the addition of PH3 to the gas-flow reduces the nanowire growth rate PH3 may be assumed to be a good alternative for n-type doping of nanowires as no further effects on the nanowire morphology is observed. The actual implementation of dopant atoms into the nanowire structure may be determined by measuring the electrical resistivity in the nanowire, and a possible four-contact structure has been designed and partly optimized for this purpose. The contact structure has been designed in three layers where two of them are produced by photolithography while the smallest layer by electron-beam-lithography. Note that the structure has not been finalized because of time limitations. Some optimization of the four nanowire contacts remains as some final lift-off problems appeared, and is assumed to be related to either an incomplete development of the smallest features or an observed resist-bubbling because of high Titanium (Ti) deposition temperature. However, a robust three-point alignment procedure has been investigated and found useful for producing accurate contacts to single nanowires and leads to the conclusion of a promising structure.
10
Bendapudi, Sree Satya Kanth. "Novel Film Formation Pathways for Cu2ZnSnSe4 for Solar Cell Applications." Scholar Commons, 2011. http://scholarcommons.usf.edu/etd/3005.
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Because of the anticipated high demand for Indium, ongoing growth of CIGS technology may be limited. Kesterite materials, which replace In with a Zn/Sn couple, are thought to be a solution to this issue. However, efficiencies are still below the 10% level, and these materials are proving to be complex. Even determination of the bandgap is not settled because of the occurrence of secondary phases. We use a film growth process, 2SSS, which we believe helps control the formation of secondary phases. Under the right growth conditions we find 1/1 Zn/Sn ratios and XRD signatures for Cu2ZnSnSe4 with no evidence of secondary phases. The optical absorption profile of our films is also a good match to the CIS profile even for films annealed at 500° C. We see no evidence of phase separation. The effect of intentional variation of the Zn/Sn ratio on material and device properties is also presented.
11
Stranks, Samuel David. "Investigating carbon nanotube - polymer blends for organic solar cell applications." Thesis, University of Oxford, 2011. http://ora.ox.ac.uk/objects/uuid:3a65d509-1610-4517-b10d-c90d832134c3.
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This thesis describes studies on nanohybrid systems consisting of single-walled carbon nanotubes (SWNTs) with monolayer coatings of semiconducting polymers. Steady-state and time-resolved optical and high-resolution microscopy experiments were used to investigate the blends. These materials show promise for use in organic photovoltaics (OPVs) owing to the high carrier mobilities and large aspect ratios of SWNTs, the controllable solubilisation of tubes with various polymers and the broad light-harvesting abilities of organic polymers. Chapters 1 and 2 introduce the theory and background behind the work and present a literature review of previous work utilising carbon nanotubes in OPV devices, revealing poor performances to date. The experimental methods used during the thesis are detailed in Chapter 3 and the solution processing techniques used to prepare the polymer–nanotube blend samples are described in Chapter 4. Chapter 5 describes a study on a nanotube blend with a thiophene polymer, a system previously unsuccessfully implemented into OPV devices. Ultrafast spectroscopic measurements showed that electrons can transfer on a 400 fs time scale from the polymer to nanotubes and the conditions to allow long-lived free charges to be produced were found. The study is extended in Chapter 6 to show that nanostructures consisting of a nanotube coated in one polymer can then be coated by a second polymer and that these nano-engineered structures could be implemented into OPV devices. The use of a competition binding process to isolate purely semiconducting nanotubes dispersed with any desired polymer is then described in Chapter 7. Finally, Chapter 8 introduces systems consisting of chains of porphyrin units, nature’s light-harvesting systems, bound to nanotubes and the blends were found to exhibit the required electronic alignment for use in OPVs. The work described in this thesis provides an explanation for the poor device behaviour of nanotube–polymer blends to date and, in particular, demonstrates several nanohybrid systems that show particular promise for improved OPV applications.
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Vyas, Niladri. "Development of novel coatings for dye-sensitized solar cell applications." Thesis, Swansea University, 2015. https://cronfa.swan.ac.uk/Record/cronfa42397.
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This research work was undertaken to solve an industrial problem related to roll-to- roll production of dye-sensitised solar cells (DSCs). It is possible to manufacture DSCs in a roll-to-roll production line on a sheet metal such as titanium. However, DSCs produced in such a way are not commercially viable due to the use of expensive titanium metal. Therefore, the intention behind this work was to utilize a cheap sheet metal such as ECCS (electro chrome coated steel) to manufacture DSCs in a roll-to-roll production facility of TATA steel Europe, as this project was funded by them. Unfortunately, ECCS corrodes in the I[-]/I[3-] redox electrolyte present in a DSC therefore, to protect ECCS from the corrosion whilst using it as a DSC substrate was the real challenging task in this research. In order to solve this problem high temperature resistant polyimide based coatings were developed which can be used to coat ECCS substrates whilst maintaining excellent dimensional stability at the DSC processing temperatures. Such coatings were electrically conducting which helped preserve the electrical conductivity of the underlying metallic substrate. Electrically conductive polyimides were developed by simply blending conductive fillers such as carbon materials and titanium nitride. It was initially thought that carbon/polyimide based coatings would be suitable for this application. However, severe interfacial charge recombination and poor reflectivity made carbon/PI coatings inferior compared to the TiN/PI coatings. TiN/PI coatings performed well but poor reflectivity produced low current outputs. Moreover, TiN/PI was found to reduce the catalytic activity of thermally deposited platinum therefore it was not useful as a counter electrode material. As a solution to these problems, TiN and carbon materials based hybrid coatings were developed. Hybrid coatings did perform efficiently in terms of overall PV performance but due to poor reflectivity, such coatings also produced low J[sc] values. However, counter electrodes prepared using hybrid coating demonstrated excellent PV performance with thermally deposited platinum. Furthermore, TCO (transparent conducting oxide) free glass substrates can also be used to manufacture low-cost PV devices when coated with these conductive coatings.
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Zhang, Rong. "Zinc Oxide Thin Films for Dye-Sensitized Solar Cell Applications." Miami University / OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=miami1186016777.
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Al-Taay, Hanaa. "Growth and characterization of silicon nanowires for solar cell applications." Thesis, Al-Taay, Hanaa (2014) Growth and characterization of silicon nanowires for solar cell applications. PhD thesis, Murdoch University, 2014. https://researchrepository.murdoch.edu.au/id/eprint/23299/.
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Silicon nanowires (SiNWs) have received considerable attention as base materials for third-generation photovoltaic (PV) devices because they lend themselves to large- scale production with enhanced light trapping and increased overall performance. Previous studies have grown SiNWs on indium tin oxide-coated glass substrates by the pulsed plasma-enhanced chemical vapour deposition method (PPECVD) using tin (Sn), aluminum (Al), gold (Au) and zinc (Zn) as catalysts.
Various catalysts (Sn, Zn, Au and Al) with thin film thicknesses from 10nm to 100nm, were used in this study of SiNW growth. Surface morphology analysis, by scanning electron microscopy (SEM) and transmission electron microscopy (TEM), of the grown SiNWs showed the influence of the catalyst type and thickness. The wires became thicker and shorter as the catalyst thickness increased. However, the SiNWs catalyzed by Al metal were thicker than those grown using Sn, Au and Zn metals. The density of the SiNWs decreased as the catalyst thickness increased. For example, the 10nm thick Al catalyst produced the greatest SiNW density of 20NW/μm2, whereas the 100nm-thick Au resulted in the lowest density of 6NW/μm2.
The effect of catalyst type and thickness on the structural properties of the grown SiNWs was investigated through X-ray diffraction (XRD). The XRD measurements showed that the SiNWs grown with Au catalysts had higher crystallinity than those grown using other catalysts. Moreover, the diffraction peaks became sharper with increasing wire diameter, indicating that the crystallinity of the grown SiNWs was enhanced. The optical properties of the prepared SiNWs were investigated by photoluminescence (PL) and Raman spectra. A red emission band was clearly observed in the PL spectra of all the prepared SiNWs. In the Raman spectrum, the first-order transverse optical mode (1TO) was exhibited in all SiNWs catalyzed using Sn, Au, Al and Zn. However, the 1TO peak location depended on the catalyst type and thickness. Important results were observed at a catalyst thickness of 80nm for all catalysts because the 1TO Raman peak was closest to the crystalline Si peak location for all the prepared samples, except for the SiNWs prepared using 100nm of Au metal.
The crystal size of the grown SiNWs was calculated from the Raman spectra. In general, the crystal size of the grown SiNWs using 10, 20, 40, 60 and 100nm of Sn, Al and Zn metals decreased with increasing thickness of catalyst. However, the SiNWs prepared using 80nm thick Sn, Al and Zn catalysts had the largest crystal size. In contrast, the crystal size of SiNWs catalyzed by Au increased with increasing the catalyst thickness.
Several designs of solar cells based on SiNWs were fabricated by the PPECVD method at 400°C on an ITO-coated glass substrate using the two most promising catalysts, Zn and Au. The first one was a p-type SiNWs/i-amorphous Si/n-type amorphous Si (p-i-n) structure using the Zn catalyst. The photocurrent density of the fabricated device was 13.3mA/cm2 and the open-circuit voltage was 0.5V. A high- performance nanowire solar cell fabricated in this work had 2.05% light conversion efficiency.
The other device structures were fabricated by doping SiNWs catalyzed with Zn and Au as p and n type to fabricate p-n homo-junction SiNW solar cells. The fabricated pn junction solar cell based on the Zn-catalyzed SiNWs showed a higher efficiency of 1.01% compared with the Au catalyzed SiNW solar cell with an efficiency of 0.67%. These promising results provide a basis for further studies aimed at optimizing the device designs.
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Kumar, R. Anil. "Studies on Solar Cell AC Parameters (Instrumentation, Measurements and Applications)." Thesis, Indian Institute of Science, 2004. https://etd.iisc.ac.in/handle/2005/116.
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Photovoltaic (PV) conversion of solar energy appears to be one of the most promising ways of meeting the increasing energy demand. In space, photovoltaic power source is the only safe alternative. Conventional silicon solar cell technologies have seen several improvements and off late GaAs/Ge and multijunction solar cells are developed to improve conversion efficiency. Demand for higher power, smaller size, lesser weight and higher efficiency has necessitated the use of high frequency switching power conditioners, which requires a better understanding of the AC characteristics of the solar cell, especially its capacitance. Solar cell is large p-n junction diode, whose AC
parameters (capacitance and resistance) varies nonlinearly with its operating voltage,
temperature and depend on the method (frequency or time domain) of measurement.Hence, studies on AC parameters of solar cells is taken up involving development of instrumentation, measurements on various types of solar cells and applications of AC parameters on switching shunt regulators.
In the present research work a measurement set-up to measure the solar cell AC parameters using impedance spectroscopy technique is established first with the commercial instruments. Here a small AC voltage (
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Kumar, R. Anil. "Studies on Solar Cell AC Parameters (Instrumentation, Measurements and Applications)." Thesis, Indian Institute of Science, 2004. http://hdl.handle.net/2005/116.
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Photovoltaic (PV) conversion of solar energy appears to be one of the most promising ways of meeting the increasing energy demand. In space, photovoltaic power source is the only safe alternative. Conventional silicon solar cell technologies have seen several improvements and off late GaAs/Ge and multijunction solar cells are developed to improve conversion efficiency. Demand for higher power, smaller size, lesser weight and higher efficiency has necessitated the use of high frequency switching power conditioners, which requires a better understanding of the AC characteristics of the solar cell, especially its capacitance. Solar cell is large p-n junction diode, whose AC
parameters (capacitance and resistance) varies nonlinearly with its operating voltage,
temperature and depend on the method (frequency or time domain) of measurement.Hence, studies on AC parameters of solar cells is taken up involving development of instrumentation, measurements on various types of solar cells and applications of AC parameters on switching shunt regulators.
In the present research work a measurement set-up to measure the solar cell AC parameters using impedance spectroscopy technique is established first with the commercial instruments. Here a small AC voltage (
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Vakkalanka, Sridevi A. "Development of window layer for high efficiency high bandgap cadmium selenide solar cell for 4-terminal tandem solar cell applications." [Tampa, Fla] : University of South Florida, 2006. http://purl.fcla.edu/usf/dc/et/SFE0001761.
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Álvarez, García Jacobo. "Characterisation of CuInS2 Films for Solar Cell Applications by Raman Spectroscopy." Doctoral thesis, Universitat de Barcelona, 2002. http://hdl.handle.net/10803/1505.
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CuInS2 is a good candidate as photovoltaic absorber for the fabrication of high efficient and low cost solar cells. In this work, the vibrational properties of CuInS2 films have been studied by means of Raman Spectroscopy, and other techniques such as XRD, TED, SEM and AES. Moreover, the CuInS2 absorber films used for the fabrication of solar cell devices have been characterised, and the sulphurisation reaction of the metallic precursors for the preparation of baseline absorbers investigated. Epitaxial and polycrystalline films were grown by a coevaporation process in a vacuum chamber containing sulphur vapour. The structural analysis of the epitaxial samples revealed that in these films two different crystallographic orderings coexist. These two polytypes of the CuInS2 compound correspond to the chalcopyrite equilibrium phase, and the "Cu-Au" metastable phase. It was found, the later to be responsible for the appearance of characteristic bands in the Raman spectra at 305 cm-1 and 60 cm-1, which had not been identified before this work. This assignment is based in both experimental results and theoretical calculations of the phonon spectra of both polytypes performed using a VFF model. On the other hand, polycrystalline films grown at different conditions were prepared in order to investigate the influence of the growth parameters upon the structural properties of the films. Cu excess conditions and growth temperatures above 470ºC lead to good quality absorbers. Moreover, the Cu excess segregates at the surface of the film as CuS, and can be easily removed by a chemical treatment in KCN. The good quality of the CuInS2 films obtained by this recipe and the wide window process (Cu/In between 1.2 and 1.8) justify this additional step for the preparation of CuInS2 films. This constitutes an important advantage with respect to the processing of CuInSe2 absorbers, for which the effect of the stoichiometric deviations is critical. The efficiency of the cells fabricated from absorbers grown under these conditions is in the range of 12%. On the contrary, films grown under Cu poor stoichiometry and/or lower temperatures present very bad crystalline quality, and lead to photovoltaic devices with very low efficiencies. It was proved that these conditions favour the formation of Cu-Au ordered domains in the films, thus deteriorating the crystalline quality of the chalcopyrite phase. Furthermore, Cu-poor conditions favour the formation of precipitates of CuIn5S8 at the bulk of the films.
Baseline sequentially processed films are obtained by the sulphurisation reaction of the metallic precursors, which are previously sputtered onto the Mo-coated glass substrate. Cu excess conditions and substrate temperatures around 500ºC are selected for the growth of these baseline absorbers. The crystalline quality of these films is similar to that of the coevaporated films grown under Cu excess conditions. Furthermore, the effect of the incorporation of Ga in the metallic precursors was also studied. The aim of introducing Ga is to increase the VOC of the final device. However, the sulphurisation of the Ga-containing precursors leads to films presenting a bilayer structure, characterised by the existence of an In rich Cu(In,Ga)S2 quaternary at the surface region of the sample, and a Ga rich Cu(In,Ga)S2 quaternary at the back region of the film. Although the homogeneity of the films could be improved by using higher sulphurisation temperatures and a Rapid Thermal Process in H2S, it was not possible to avoid the accumulation of Ga close to back region of the films. The explanation for the structure of these films was provided by the analysis of samples quenched at different stages of the sulphurisation reaction, which allow establishing the fundamental steps of the sulphurisation reaction of the metallic layers.
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Karaman, Mehmet. "Characterization And Fabrication Of Silicon Thin Films For Solar Cell Applications." Master's thesis, METU, 2011. http://etd.lib.metu.edu.tr/upload/12613598/index.pdf.
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In this thesis study, fabrication and characterization of silicon thin films
prepared by magnetron sputtering and electron beam evaporation for solar
cell applications have been investigated. In the first part of the study,
magnetron sputtering method was used to fabricate thin hydrogenated
amorphous silicon (a-Si:H) film on a Si substrate. Some samples were
prepared on glass substrate for the basic characterizations like transmission
and resistivity. Dark and illuminated I-V characteristics of the silicon
heterojunction (SHJ) solar cells were studied as a function of material type
and process parameters. It was observed that devices show diode
characteristics, however their response to the illumination was quite weak.
Low performance of the devices was discussed in terms of the resistivity and
dopability of the sputtered film. The second part of the thesis deals with the
fabrication and characterization of thin polysilicon films fabricated by e-beam
evaporation. In order to dope the deposited Si films, a very thin boron film
v
was deposited by e-beam evaporation on SiO2 surface thermally grown on a
Si wafer. Then an a-Si was evaporated by the same technique. Samples
were annealed for polysilicon formation by using the technique called solid
phase crystallization (SPC). The annealing was performed in two steps. The
first step was the nucleation part, carried out at 475°C for 8 hours and the second step was the diffusion and crystallization parts that are accomplished at 900°
C for several minutes. The Raman measurements revealed out the crystallinity and grain size. The crystallinity of the polysilicon thin films was also identified by X-Ray diffraction measurements. Finally, the Secondary Ion Mass Spectroscopy (SIMS) analysis was carried out to find out the amount of boron that diffuses into Si film. It was found that a graded boron profile, which is desirable for the solar cell applications, was achieved.
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Ferrada, Martínez Pablo [Verfasser]. "Diffusion through Oxide Barriers for Solar Cell Applications / Pablo Ferrada Martínez." Konstanz : Bibliothek der Universität Konstanz, 2012. http://d-nb.info/1023652773/34.
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Liu, Piao. "Heterojunctions and Schottky Diodes on Semiconductor Nanowires for Solar Cell Applications." UKnowledge, 2010. http://uknowledge.uky.edu/gradschool_diss/77.
Full textAbstract:
Photovoltaic devices are receiving growing interest in both industry and research institutions due to the great demand for clean and renewable energy. Among all types of solar cells, cadmium sulfide (CdS) – cadmium telluride (CdTe) and cadmium sulfide (CdS) - copper indium diselenide (CuInSe2 or CIS) heterojunctions based thin film solar cells are of great interest due to their high efficiency and low cost. Further improvement in power conversion efficiency over the traditional device structure can be achieved by tuning the optical and electric properties of the light absorption layer as well as the window layer, utilizing nano template-assisted patterning and fabrication. In this dissertation, simulation and calculation of photocurrent generation in nanowires (NW) based heterojunction structure indicated that an estimated 25% improvement in power conversion efficiency can be expected in nano CdS – CdTe solar cells. Two novel device configurations for CdTe solar cells were developed where the traditional thin film CdS window layer was replaced by nanowires of CdS, embedded in aluminum oxide matrix or free standing. Nanostructured devices of the two designs were fabricated and a power conversion efficiency value of 6.5% was achieved. Porous anodic aluminum oxide (AAO) was used as the template for device fabrication. A technology for removing the residual aluminum oxide barrier layer between indium tin oxide (ITO) substrate and AAO pores was developed. Causes and remedies for the non-uniform barrier layer were investigated, and barrier-free AAO on ITO substrate were obtained. Also, vertically aligned nanowire arrays of CIS of controllable diameter and length were produced by simultaneously electrodepositing Cu, In and Se from an acid bath into the AAO pores formed on top of an aluminum sheet. Ohmic contact to CIS was formed by depositing a 100 nm thick gold layer on top and thus a Schottky diode device of the Au/CIS nanowires/Al configuration was obtained. Material properties of all these nanowires were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), absorption measurement. Current-voltage (I-V), capacitance-voltage (C-V) and low-temperature measurements were performed for all types of devices and the results were analyzed to advance the understanding of electron transport in these nano-structured devices.
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Esmaeel, Omar Mohammed. "Synthesis and characterisation of new conjugated polymers for solar cell applications." Thesis, University of Sheffield, 2018. http://etheses.whiterose.ac.uk/22302/.
Full textAbstract:
Significant efforts were conducted during the last few decades to find a new alternative energy resource that replaces the current conventional resources and reduce emission of greenhouse gasses and Global Warming. The traditional silicon-based inorganic solar cells are efficient but their high cost limits their use. Organic photovoltaic devices offer many features including the low production costs and flexibility of devices. In addition, these materials are commercially available and easy to process compared to inorganic materials. The development of bulk heterojunction photovoltaic devices with high power conversion efficiency is still under investigation. Moreover, enormous numbers of conjugated polymers were synthesised and studied to achieve high power conversion efficiencies by designing conjugated polymers exploiting π-electrons delocalization within the polymer backbone. The solubility of conjugated polymers is an important matter to consider, so attaching alkyl chains to the backbone of the polymer will not only enhance the solubility of these materials but also increase the charge carrier mobility through the increase of molecular weight of conjugated polymer. In this thesis, different studies have discussed the synthesis of donor-acceptor (D-A) conjugated polymers based on benzothiadiazole (BTD) as an acceptor with donor units such as carbazole and fluorene using direct hetero arylation (DHA) polymerisation were undertaken. The synthesis of a series of conjugated polymers based on fluorinated or non-fluorinated BTD units with molecules such as naphthalene, anthracene, pyrene, carbazole, fluorene and bithiophene-based donor units is presented. The impact of fluorine substitution attached to polymer chains has clearly shown deep HOMO levels in the resulting materials, which agrees with findings in the literature. Another aspect was covered in this thesis which is the impact of extending the π-conjugated system by adding additional aromatic units to the polymers backbone. Interestingly, the results from UV-visible and cyclic voltammetry are both satisfying in obtaining low bandgap polymers regardless the type of donor units used in the conjugated polymer prepared.
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Salomon, Ashley. "Oxygen precipitate studies in silicon for gettering in solar cell applications." Thesis, Massachusetts Institute of Technology, 2001. http://hdl.handle.net/1721.1/114090.
Full textAbstract:
Thesis: S.B., Massachusetts Institute of Technology, Department of Materials Science and Engineering, 2001.Cataloged from PDF version of thesis.
Includes bibliographical references (page 31).
Oxygen precipitates in silicon can be used (in a process called internal gettering) as sites of heterogeneous nucleation of precipitates of iron and other transition metal that are harmful to solar cell device operation. Oxygen precipitate densities in p- (10¹⁴ boron atoms/cm³) wafers were quantified using chemical etch techniques. The precipitate densities were then used to estimate times to getter iron based on a diffusion limited precipitation model. Oxygen precipitate densities in p++ (10¹⁹ boron atoms/cm³) wafers were quantified using chemical etch techniques. High levels of boron in p++ wafers make quantifying precipitate densities particularly difficult, via etching, or other methods because precipitate densities in highly doped wafers are very high and the size of precipitates small.
by Ashley Salomon.
S.B.
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Waggett, Jonathan. "The study of inorganic semiconductor quantum dots for solar cell applications." Thesis, University of Bristol, 2005. http://hdl.handle.net/1983/916bf29c-07eb-4601-be30-534e81635c1b.
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Schnabel, Manuel. "Silicon nanocrystals embedded in silicon carbide for tandem solar cell applications." Thesis, University of Oxford, 2014. http://ora.ox.ac.uk/objects/uuid:da5bbb64-0bcd-4807-a9f3-4ff63a9ca98d.
Full textAbstract:
Tandem solar cells are potentially much more efficient than the silicon solar cells that currently dominate the market but require materials with different bandgaps. This thesis presents work on silicon nanocrystals (Si-NC) embedded in silicon carbide (SiC), which are expected to have a higher bandgap than bulk Si due to quantum confinement, with a view to using them in the top cell of a tandem cell. The strong photoluminescence (PL) of precursor films used to prepare Si-NC in SiC (Si-NC/SiC) was markedly reduced upon Si-NC formation due to simultaneous out-diffusion of hydrogen that passivated dangling bonds. This cannot be reversed by hydrogenation and leads to weak PL that is due to, and limited by, non-paramagnetic defects, with an estimated quantum yield of ≤5×10-7. Optical interference was identified as a substantial artefact and a method proposed to account for this. Majority carrier transport was found to be Ohmic at all temperatures for a wide range of samples. Hydrogenation decreases dangling bond density and increases conductivity up to 1000 times. The temperature-dependence of conductivity is best described by a combination of extended-state and variable-range hopping transport where the former takes place in the Si nanoclusters. Furthermore, n-type background doping by nitrogen and/or oxygen was identified. In the course of developing processing steps for Si-NC-based tandem cells, a capping layer was developed to prevent oxidation of Si-NC/SiC, and diffusion of boron and phosphorus in nanocrystalline SiC was found to occur via grain boundaries with an activation energy of 5.3±0.4 eV and 4.4±0.7 eV, respectively. Tandem cells with a Si-NC/SiC top cell and bulk Si bottom cell were prepared that exhibited open-circuit voltages Voc of 900 mV and short-circuit current densities of 0.85 mAcm-2. Performance was limited by photocurrent collection in the top cell; however, the Voc obtained demonstrates tandem cell functionality.
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Joshi, Monali-Bianca Dileep. "Fabrication of engineered composite semiconductor substrates for flexible solar cell applications." Diss., Restricted to subscribing institutions, 2009. http://proquest.umi.com/pqdweb?did=1905650241&sid=1&Fmt=2&clientId=1564&RQT=309&VName=PQD.
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Calabrese, Anna. "Design, Synthesis and Characterization of Random Copolymers for Photovoltaic Applications." Thesis, Università degli Studi di Catania, 2011. http://hdl.handle.net/10761/225.
Full textAbstract:
In this work of thesis is reported the synthesis and the optoelectronic characterization of a new family of random conjugated copolymers based on 9,9-bisalkylfluorene, thiophene and benzothiadiazole monomers unit synthesized by a palladium-catalyzed Suzuki cross-coupling reaction. The photophysical, thermal, electrochemical properties were investigated. The electronic structures of the copolymers were simulated via quantum chemical calculations. Bulk heterojunction solar cells based on these copolymers blended with fullerene, exhibited power conversion efficiency as high as 1% under illumination of 97 mW/cm2
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Addo, Ernest A. "Fritless doped self-aligning thick film metallization fo crystalline solar cell applications." Click to view the dissertation via Digital dissertation consortium, 2004.
Find full textAbstract:
Thesis (Ph. D.)--University of Delaware, 2004.Principal faculty advisor: S. Ismat Shah, Robert L. Opila, Dept. of Materials Science & Engineering. Includes bibliographical references (leaves 171-178).
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Ng, Annie, and 吳玥. "Polymer blend film for photovoltaic applications optical characterization and solar cell performance." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2013. http://hdl.handle.net/10722/196013.
Full textAbstract:
Sunlight is sustainable, clean and readily available energy source, which is one of the potential alternatives to the traditional energy sources. Recently, the organic photovoltaics (OPVs), in particular polymer solar cells (PSCs), have attracted increasing attention owing to their outstanding properties such as low cost, lightweight, flexible, allowing vacuum-free fabrication process and thin-film architecture. These advantageous material and manufacturing features of PSCs provide the opportunities for many novel applications. However, the lower power conversion efficiencies (PCEs) of PSCs compared to inorganic solar cells hinder their competition in the marketplace.
This thesis covers the basic principles of the PSC, strategies for enhancing PCEs as well as the recent development of PSCs. The importance of the source materials has been also demonstrated and discussed. Due to a large number of possibilities, limited resources and time, it is not feasible to do all the work experimentally. Therefore, for continuing advance development of PSCs, the device performance should be modeled as a function of material parameters, which requires the knowledge of material properties, in particular the complex index of refraction N= n - ik. Accurate determination of the optical functions of the active layers and light trapping layers commonly used in PSCs by using the spectroscopic ellipsometry (SE) has been demonstrated. In order to acquire reliable solutions, the methodology including multiple sample analysis, combinations of different measurement techniques, selection of models, the rigorous fitting procedures and the independent verification have been proposed. The obtained information can be used in the simulation to optimize device architectures, model device performance as well as characterize novel materials.published_or_final_version
Physics
Doctoral
Doctor of Philosophy
30
Yuan, Guangbi. "Synthesis and Applications of Vertically Aligned Silicon Nanowire Arrays for Solar Energy Conversion." Thesis, Boston College, 2012. http://hdl.handle.net/2345/3738.
Full textAbstract:
Thesis advisor: Dunwei WangSolar energy, the most abundant and free renewable energy, holds great promise for humanity's sustainable development. How to efficiently and inexpensively capture, covert solar energy and store it for off peak usages constitutes a grand challenge for the scientific community. Photovoltaic devices are promising candidates but are too costly to be implemented in large scales. On a fundamental level, this is due to the dilemma that the length scales of the optical pathways and electrical pathways often do not match within the photovoltaic device materials. Consider traditional Si solar cell as an example, effective light absorption requires up to hundreds of microns material while the photogenerated charge carries can only diffuse less than a few microns or even shorter before recombination. Such a problem may be solved by using Si nanowires (SiNWs) because vertically aligned nanowires can orthogonalize the light absorption and charge carrier collection pathways, thereby enabling the use of low-cost materials for practically appealing solar energy conversion devices. The objective of this thesis work is to explore low-cost synthesis of vertically aligned SiNW arrays and study their performance in both solar energy conversion and storage devices. We developed a method to synthesize vertically aligned SiNW arrays in a hot-wall chemical vapor deposition system with tunable length, doping level, and diameter for systematical studies. Empowered by the synthetic control, various types of vertical SiNW arrays were characterized by both steady-state (photoelectrochemical measurement) and transient (electrochemical impedance spectroscopy) techniques in a photoelectrochemical cell platform. Additionally, SiNWs were demonstrated to be a promising candidate for photoelectrochemical aromatic ketone reduction and CO₂ fixation. The reactions studied in this thesis are in close resemblance to natural photosynthesis and the resulted product molecules are precursors to nonsteroidal anti-inflammatory drugs, ibuprofen and naproxen. Lastly, vertical transparent conductive oxide nanotubes were prepared from vertical SiNW array templates. Ultrathin hematite (Fe₂O₃) film was coated on the nanotube scaffold by atomic layer deposition to form a heteronanostructure photoelectrode for efficient solar water oxidation. Our results highlight the potential of vertically aligned SiNW arrays in solar cell, solar water splitting and artificial photosynthesis applications
Thesis (PhD) — Boston College, 2012
Submitted to: Boston College. Graduate School of Arts and Sciences
Discipline: Chemistry
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Johansson, Erik. "Interfaces in Dye-Sensitized Oxide / Hole-Conductor Heterojunctions for Solar Cell Applications." Doctoral thesis, Uppsala : Acta Universitatis Upsaliensis : Universitetsbiblioteket [distributör], 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-6892.
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Ekanayake, Gayani. "Polycrystalline silicon thin films by aluminium induced crystallisation for solar cell applications." Thesis, London South Bank University, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.435201.
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Looney, Erin Elizabeth. "Oxygen defect engineering for silicon solar cell applications : process design and modeling." Thesis, Massachusetts Institute of Technology, 2017. http://hdl.handle.net/1721.1/111715.
Full textAbstract:
Thesis: S.M., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2017.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 78-82).
One of the main remaining impurities that lowers efficiencies of silicon solar cells are oxygen ring defects that are incorporated into the material during growth. These defects decrease overall cell efficiencies by around 20% (rel.) resulting in a yield loss of about 1/4 h of each monocrystalline silicon ingot. To control the oxygen defects and put them in the least harmful form possible, a new cell processing step call tabula rasa (TR) is explored. TR is a high temperature process for a short duration. In this work, TR is found to be a kinetically-limited process through several oxygen precipitate dissolution experiments from which the activation energy of dissolution is found to be equivalent to the migration enthalpy for oxygen in silicon. With this knowledge, a predictive kinetic model is built which can be used for process optimization. A multiscale end-to-end model is also developed to determine the effect of rings on cell performance. Using oxygen defect parameter inputs, device modelling, and a spatially resolved two diode mesh, PL images are transformed into current maps and used to determine cell efficiencies for inhomogeneously distributed defects. A reduction in efficiency for cells with ring defects is simulated for several ring defect concentrations and compared to a non-defective cell. Another strategy for lowering cost and mitigating oxygen ring defects is using thinner silicon absorbers with inherent defect tolerance. Using the multiscale modeling platform described above, thin silicon wafers are compared to typical cells. It is shown that thin cells with ring defects perform with higher efficiencies, with less than half the material used. The thin silicon strategy is compared with the TR process addition, and future work is outlined to further explore these oxygen mitigation options.
by Erin Elizabeth Looney.
S.M.
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Jamshidi, Zavaraki Asghar. "Engineering Multicomponent Nanostructures for MOSFET, Photonic Detector and Hybrid Solar Cell Applications." Doctoral thesis, KTH, Teoretisk kemi och biologi, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-177609.
Full textAbstract:
Silicon technologyhas been seekingfor a monolithic solution for a chip where data processing and data communication is performed in the CMOS part and the photonic component, respectively. Traditionally, silicon has been widely considered for electronic applications but not for photonic applications due to its indirect bandgap nature. However, band structure engineering and manipulation through alloying Si with Ge and Sn has opened new possibilities. Theoretical calculations show that it is possible to achieve direct transitions from Ge ifit is alloyed with Sn. Therefore, a GeSn system is a choice to get a direct bandgap. Extending to ternary GeSnSi and quaternary GeSnSiCstructures grown on Si wafers not only makes the bandgap engineering possible but also allowsgrowing lattice matched systems with different strain and bandgaps located in the infrared region. Different heterostructures can be designed and fabricated for detecting lightas photonic sensing oremitting the light as lasers. Alloying not only makes engineering possible but it also induces strain which plays an important role for electronic applications. Theoretical and experimental works show that tensile strain could increase the mobility, which is promising for electronic devices where high mobility channels for high performance MOSFETs is needed to speed up the switching rate. On the other hand, high n-doping in tensile strains in p-i-n structures makesΓ band transitions most probable which is promising for detection and emission of the light. As another benefit of tensile strain, the direct bandgap part shrinks faster than the indirect one if the strain amount is increased. To get both electronic and photonic applications of GeSn-based structures, two heterostructures (Ge/GeSn(Si)/GeSi/Ge/Si and Ge/GeSn/Si systems), including relaxed and compressive strained layers used to produce tensile strained layers, were designed in this thesis. The low temperature growth is of key importance in this work because the synthesis of GeSn-based hetrostructures on Si wafers requires low thermal conditions due tothe large lattice mismatch which makes them metastable. RPCVD was used to synthesize theseheterostructures because not only it offers a low temperature growth but also because it is compatible with CMOS technology. For utilization of these structures in devices, n-type and p-type doping of relaxed and compressive strained layers were developed. HRRLMs, HRTEM, RBS, SIMS, and FPP techniques were employed to evaluatestrain, quality, Sn content and composition profile of the heterostructures. The application of GeSn-based heterostructures is not restricted to electronics and photonics. Another application investigated in this work is photovoltaics. In competition with Si-based solar cells, which have, or areexpected to have,high stability and efficiency, thirdgeneration solar cells offer the use of low cost materials and production and can therefore be an alternative for future light energy conversion technology. Particularly, quantum dot sensitized solar cells are associated with favorable properties such as high extrinsic coefficients, size dependent bandgaps and multiple exciton generation and with a theoretical efficiencyof 44%. In this work, two categories of QDs, Cd-free and Cd-based QDs were employed as sensitizers in quantum dot sensitized solar cells (QDSSCs). Cd-based QDs have attracted large interest due to high quantum yield,however, toxicityremains still totheir disadvantage. Mn doping as a bandgap engineering tool for Cd-based type IIZnSe/CdS QDs wasemployed to boostthe solar cell efficiency. Theoretical and experimental investigations show that compared to single coreQDSSCs,typeII core-shells offer higher electron-hole separation due to efficient band alignment where the photogenerated electrons and holes are located in the conduction band of the shell and valence band of the core, respectively. This electron-hole separation suppresses recombination and by carefully designing the band alignment in the deviceit can increase the electron injection and consequently the power conversion efficiency of the device. Considering eco-friendly and commercialization aspects, three different “green” colloidal nanostructures having special band alignments, which are compatible for sensitized solar cells, were designed and fabricated by the hot injection method. Cu2GeS3-InP QDs not only can harvest light energy up to the infraredregion but can also be usedastypeII QDs. ZnS-coating was employed as a strategy to passivate the surface of InP QDs from interaction with air and electrolyte. In addition, ZnS-coating and hybrid passivation was applied for CuInS2QDs to eliminate surface traps.QC 20151125
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Benson, Jessica J. "Spectroscopic studies of organic donor-acceptor blend films for solar cell applications." Thesis, Imperial College London, 2007. http://hdl.handle.net/10044/1/11386.
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Using several organic electron donor and electron acceptor materials, solution cast blend films were studied to better understand charge separation and excited state formation in thin films for organic solar cell applications.
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Zhou, Xuan. "Structural engineering of porphyrin small molecules for bulk heterojunction organic solar cell applications." HKBU Institutional Repository, 2018. https://repository.hkbu.edu.hk/etd_oa/563.
Full textAbstract:
Organic donor and acceptor have promised the better future energy technologies to alleviate global energy demand and environmental issues. And nowadays they begin to come true in bulk heterojunction organic solar cells (BHJ OSCs) with advantages of low-cost, light-weight, large-area, flexibility, and with high efficiencies (PCEs) of over 14% for converting solar energy to electricity. Porphyrins are unique potential for artificial photocatalysis but their application in BHJ OSCs are still limited by the PCEs less than 10%. This complicacy comes from their inadequate spectral absorptions and the imperfect morphologies. In this thesis, we devote to chemical modification of acceptor-π-porphyrin-π-acceptor (A-π-Por-π-A) structural molecules to enhance their spectral absorptions and phase-separation functions with fullerene acceptor. Firstly, chemically driving J-aggregates have been studied on the new A-π-Por-π-A porphyrin molecule, which could improve the phase-separation of its blend film with PC71BM and and enhance its performance in BHJ OSCs with PCE up to 8.04%. Secondly, two new benzodithiophene (BDT) π-bridged A-π-Por-π-A molecules have been prepared with complementary absorption between the Soret and Q bands. The devices based on the blend fims of the porphyrin donor and PC71BM acceptor exhibit full spectral photocurrent generation and impressive PCEs up to 7.92%. Thirdly, we further extended the π-conjugation of the above BDT π-brigded A-π-Por-π-A molecules by inserting alkyl chain substituted thiophene derivatives into their backbones, resulting in new porphyrin molecules with UV-visible-near-infraed absorption spectra. Using those porphyrin molecules as donor and PCBM as acceptor, the devices show full spectra photocurrent generatoion and appropriate film morphology, resulting in high PCE up to 8.59%. Besides, photocatalysis is also a new promising technology to generate renewable energy. We herein develop new low-cost and noble-metal-free photocatalysts based on Co(OH)2 modified CdS nanowires and applied them for visible light driven hydrogen production from water-splitting. The optimum H2 production rate reaches 14.43 mmol·h−1·g−1 under (λ ≥ 420 nm) upon visible light irradiation, which is 206 and 3 times larger than that of the pristine CdS NWs and 1 wt% Pt-CdS NWs, respectively. The results indicate the promising application of earth-abundant Co(OH)2 as alternative cocatalysts of noble metals.
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Chow, Simon Ka Ming. "Integration of High Efficiency Solar Cells on Carriers for Concentrating System Applications." Thèse, Université d'Ottawa / University of Ottawa, 2011. http://hdl.handle.net/10393/19932.
Full textAbstract:
High efficiency multi-junction (MJ) solar cells were packaged onto receiver systems. The efficiency change of concentrator cells under continuous high intensity illumination was done. Also, assessment of the receiver design on the overall performance of a Fresnel-type concentration system was investigated.
We present on receiver designs including simulation results of their three-dimensional thermal operation and experimental results of tested packaged receivers to understand their efficiency in real world operation. Thermal measurements from solar simulators were obtained and used to calibrate the model in simulations. The best tested efficiency of 36.5% is obtained on a sample A receiver under 260 suns concentration by the XT-30 solar simulator and the corresponding cell operating temperature is ~30.5°C. The optimum copper thickness of a 5 cm by 5 cm simulated alumina receiver design was determined to be 6 mm and the corresponding cell temperature under 1000 suns concentration is ~36°C during operation.
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Rauer, Michael [Verfasser]. "Alloying from Screen-printed Aluminum Pastes for Silicon Solar Cell Applications / Michael Rauer." Konstanz : Bibliothek der Universität Konstanz, 2015. http://d-nb.info/1079010297/34.
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Engman, Jessica. "Experimental study of Cu2ZnSn(Se,S)4 thin films for solar cell applications." Thesis, Uppsala universitet, Fasta tillståndets elektronik, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-155091.
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Cu2ZnSn(Se,S)4 (CZT(Se,S)) has recently been shown to be a promising material to use in thin film solar cells. It has a band gap of between 1eV (CZTSe) and 1.5eV (CZTS). CZT(Se,S) solar cells have reached 10% efficiency. The aim of this project was to find an effective way to selenise metallic Cu, Zn, Sn films in order to produce Cu2ZnSnSe4 (CZTSe) films, without destroying the metallic molybdenum (Mo) back contact. Another aim was to make films containing both Se and S and to study the possibility to achieve a controlled S/Se ratio in the films. Selenisation and sulfurisation reactions were carried out in quartz ampoules and samples were characterized using scanning electron microscopy, x-ray diffraction and energy dispersive microscopy. Since Mo reacts rapidly with Se, experiments with selenisation and sulfurisation of plain Mo films were performed. The time and temperature dependence of the thickness of the reacted layer was studied, and it was found that Se reacts much faster with Mo than S does. Pre-sulfurisation of Mo appeared to hinder Se from reacting with the Mo. The next step was to react precursor films to make CZTSe and CZT(Se,S) absorber layers. For mixed Se and S samples, the result is the same as for plain Mo samples; pre-sulfurisation, or inclusion of S in the precursor layer, can prevent selenisation of the Mo. The S/Se ratio was controlled with reaction time. The best efficiency of 3.2% was obtained for a CZTSe sample while the best CZT(Se,S) sample gave 2.3%.
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Sampson, Karen E. "NANOPOROUS ALUMINA ON MOLYBDENUM AND ITO SUBSTRATES FOR NANO-HETEROJUNCTION SOLAR CELL APPLICATIONS." UKnowledge, 2007. http://uknowledge.uky.edu/gradschool_theses/447.
Full textAbstract:
Indium tin oxide (ITO) and molybdenum are substrates of choice in the manufacture of the CdS-CIS photovoltaic cell, which is the base for the leading thin-film solar cell technology. Substantial advancement in this technology is expected if these devices can be made in nanoporous alumina (AAO) templates. The first step to this endeavor is to learn to form AAO templates on molybdenum and ITO substrates. This was accomplished, and the results are reported in this thesis. Starting substrates were glass, coated with either a thin molybdenum layer or a thin ITO layer. Aluminum was deposited on top of this conducting substrate. Oxalic acid was used as the electrolyte for anodization. In the case of molybdenum substrates, average pore diameter was 45 nm when an anodization voltage of 40 volts was used for approximately 46 minutes; current density was approximately 23 amps/sq. m. In the case of ITO substrates, pores of 45 nm diameter were obtained for approximately 20 minute anodization at 40 V; current density was 40 amps/sq. m; annealing of aluminum layer prior to anodization, at 550 oC (degrees Centigrade) for 90 minutes was needed to obtain good pores. A one micrometer thick CdS layer was electrodeposited inside the AAO pores on top of the ITO substrate. In preliminary experiments, CdS/Cu2S photovoltaic heterojunctions with an open circuit voltage of 242 mV were formed inside the nanopores.
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Wen, Kuo Yu, and 郭鈺雯. "Development of Solar Cell Applications." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/00449123099254517619.
Full textAbstract:
碩士大葉大學
工學院碩士在職專班
101
The issues of environmental consciousness and clean energy are getting more important nowadays. Among them, there is no doubt that the use of solar energy catches more attention around the world. Scientists from Bell Labs invented the solar cell in 1954 and created a new revenue stream via its solar cell business. As so far, there are several different kinds of solar cells, including silcon based, thin film and new concept. However, solar photovoltaic cells have more production costs than other energy. Therefore, many governments fund subsidies to help the solar photovoltaic industries and encourage them to make big savings on costs through greater conversion efficiency of solar photovoltaic cells. Nowadays the use of solar photovoltaic cells plays an important role in every one’s daily life. Therefore, solar photovoltaic industries focus on building integrated photovoltaic (BIPV) . And they can be connected to many other industries, such as agriculture, fisheries and Animal husbandry in Taiwan. Besides, high concentration photovoltaic (HCPV) have been mainly introduced in large solar photovoltaic power plants. Based on the profound foundation of the semiconductor industry and the largest amount of concentrator photovoltaic equipment, called metal-organic chemical vapor deposition system in the world, Taiwan’s solar photovoltaic industries definitely take a great advantage in the future.
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Tummala, Rajesh. "Solution processed optical coatingsfor solar cell applications." 2009. http://hdl.handle.net/10106/1708.
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jeng, cheng, and 陳政傑. "Nanostructure for dye-sensitized solar cell applications." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/87664066912823098864.
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碩士國立中正大學
光機電整合工程所
98
In this study, we fabricated a dye-sensitized solar cell (DSC) using an electrode of the titanium dioxide (TiO2) hollow spheres, and examined the photovoltaic performance under simulated sunlight. TiO2 hollow spheres were fabricated by burning out the PS balls in the TiO2 Sol-gel paste. The efficiency of DSSC with 400nm diameter hollow spheres in 10 μm P10 TiO2 film can reach to 4.87%. (about 40% improvement) The 2nd microstructure of TiO2 hollow spheres were fabricated by using Pulsed Laser Deposition (PLD) techniques. This film incorporated multi hollow sphere microstructures would produce efficient electron transport paths and mitigate recombination processes. This DSSC with multi hollow sphere microstructure show a high open-circuit voltage(Voc) of 7.5V and Fill Factor(F.F.) of 0.7 under an illumination of one sun (AM1.5 global, 100 mW/cm2) .
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Huang, Shih-Han, and 黃詩涵. "Carrier Dynamics in Materials for Solar Cell Applications." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/10327427225059706622.
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碩士國立交通大學
電子物理系所
100
Carrier dynamics in materials for solar cell applications have been investigated by time-resolved photoluminescence. One is InAs self-assembled quantum dots (QDs) covered with a thin AlxGa1-xAs0.8Sb0.2 layer. There is a type I-like transition in type II InAs/GaAsSb QDs due to the recombination of electrons from QDs and holes residing in extended levels composed by the capping layer and the QDs, which is activated by thermal excitation. With the increasing Al content, a blueshift in the QD emission peak and a shortening of the PL decay time are observed, indicating that the band alignment can be controlled by varying the Al content in the AlGaAsSb capping layer. Increasing the valence band offset tend to push the hole wave function into QDs, which in turn improves the overlap between the electron and hole wave functions. According to the experimental results and the theoretical calculations based on eight-band k ⃑∙p ⃑ model, we demonstrate that the AlxGa1-xAs0.8Sb0.2 covered InAs QDs exhibit a type-I band alignment when the Al content exceeds 0.2.Another one is CIGS solar cell. High conversion efficiency in CIGS solar cell is associated with stronger PL intensity and longer carrier lifetime, which is caused by the domination of SRH recombination at room temperature. Besides, radiative recombination in CIGS device is strongly affected by the built-in electric field. Therefore, the intrinsic carrier lifetime can be obtained by injecting higher carrier density.
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Lin, Jui Chan, and 林瑞展. "Fabrication of AZO films for solar cell applications." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/70207104997720001702.
Full textAbstract:
碩士中興大學
電機工程學系所
95
Aluminum doped zinc oxide (AZO) thin films deposited by RF sputter and the effects on electrical properties of amorphous silicon thin-film solar cells were studied. The electrical, optical, and structural properties of the AZO films were investigated as a function of the substrate temperature and the RF power with a background gas Ar. Argon gas pressure during deposition was kept at 5×10-2 torr. The substrate temperature and the RF power were ranging from 27 to 380℃ and 40 to 160 W, respectively. The transmittances of all the samples were above 85% in the wavelength of 400-800nm. The optical properties of the films, which change in accordance with the Burstein-Moss effect, are consistent with the observed changes in electrical properties. Optical band gap widens with carrier concentration. For structural analysis, crystallinity and surface morphology of AZO films were investigated by X-ray diffraction (XRD) and SEM, respectively. It is found that the roughness of the samples increases with substrate temperature. In order to improve the electrical characteristics of AZO films, a novel post H2-plasma treatment for 15-120 min was performed. The sheet resistances of the AZO films decreased form 516.3 to 90.1 Ω/sq. However, high H2-plasma power would damage the film surface and increase the sheet resistance. The post H2-plasma treated AZO films had been applied for amorphous silicon thin-film solar cells and better short current and efficiency of cells were obtained.
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Lin, Yi-Dong, and 林毅東. "Plasmonic-assisted transparent metallic electrode for solar cell applications." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/98267322709883572489.
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碩士國立東華大學
光電工程研究所
98
In this thesis, we simulate the optical properties of one-dimensional periodically structures. In structure, we change the thickness、period、width ratio of aluminum grating，and vary the distance between the aluminum grating to study the structure by changing the parameters of the impact on the transmission, and then find the high transmission of metal electrodes, and use it in solar cell. In order to improve the current spreading of a solar cell, a comb-shaped metal electrode is usually applied on the transparent conductive oxide (TCO). Nevertheless, the opaque metal electrode limits the optical efficiency. In this study, two kinds of metallic structure are proposed as a transparent metal electrode，those metal electrode were composed of single layer plasmonic grating structure and stacked plasmonic grating structure, to make a comb-shaped metal electrode into grating that are transparent can improve optical efficiency greatly.(1)The single layer plasmonic structure has higher overall transmission efficiency than the stacked one. (2)Owing that the stacked structure has a larger metal-covered area, the transverse resistance of the stacked structure can be lower than that of single layer structure.(3) We can find the best transmittance 44.45% for single layer metal grating at period=100nm, tm=110nm, and 31.33% for stacked plasmonic grating structure at period=100nm, tm=50nm, tg=50nm (4) In the four materials, Au, Ag, Cu and Al, high transmittance occurs when using Al and Ag for metal electrode. We choose Al for the material of metal electrode because of Al is much cheaper than Ag.(5)single layer metal grating in the sub-wavelength thickness of aluminum, will not have much effect on transmission. Finally，we use two kinds of metallic structure are proposed as a transparent metal electrode in a-Si solar cell. Two kinds of metallic structure are proposed as a transparent metal electrode simultaneously proving higher transmission and conductivity. In addition We can according to different needs, to adjust the incident light. Therefore, the highest transmission area of the single layer plasmonic grating is due to the waveguide mode coupled by the periodic grating or caused by the SP resonance. It will be useful for solar cell application.
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Huang, Guo-Yang, and 黃國洋. "Applications of Nanocrystalline TiO2 for Dye-Sensitized Solar Cell." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/54357623814088331192.
Full textAbstract:
碩士南台科技大學
化學工程與材枓工程系
95
Abstract The efficiency of dye-sensitized solar cells(DSSCs) has been investigated under different conditions. The optimal conditions were systematically studied by using the statistical experimental strategy. At the optimal conditions, a high efficient dye-sensitized solar cell has been assembled. Commercial TiO2 paste and sol-gel TiO2 paste derived from our preparation were used to make nanopourous TiO2 electrode, and the platinum counter-electrodes were prepared using the sputtering method and the spin-coating methods, respectively. The liquid electrolyte, 0.1M I2、0.5M 4-tert-Butylpyridine(TBP)、0.1M LiI and 3-methoxypropionitrile(MPN) or acetonitrile(ACN) , was used in the photovoltaic devices. Furthermore, the higher photovoltaic conversion efficiency was obtained by using the spin-coating method to make Pt counter-electrode in the device. In order to increase the efficiency of the dye-sensitized solar cell, we used acetonitrile(ACN) as the solvent to make up liquid electrolyte and get the higher photovoltaic conversion efficiency to 4.2% on the 30Ω FTO substrate. When we changed the FTO glass as substrate , a higher efficiency of 6.2% device was obtained under same other conditions . Finally , we used the statistical experimental strategies to generalize the best conditions for the component of dye-sensitized solar cell in order to obtain the higher photovoltaic conversion efficiency. The optimal conditions as follows: 10Ω FTO substrate , 8μm TiO2 film thickness , ACN as solvent for electrolyte , 15% PEG content in TiO2 paste and spin-coated Pt counter-electrode . The highest efficiency is about 6.6% .
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Hsiang-hsiu, Tseng, and 曾祥修. "Polymorphous Aluminum Induced Poly-crystallization for Solar Cell Applications." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/73716460886966603031.
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碩士南台科技大學
光電工程系
98
In this study, we used photolithography to fabricate aluminum layer with various surface patterns that can selectively induce crystallization of silicon, with the surface roughening treatment of transparent electrode, light can pass through amorphous silicon and poly-silicon and thus increase the light absorption range (380 nm ~ 1100 nm) in silicon thin film solar cells, leading to the enhancement in the power conversion efficiency. Tow circular diameters of 5 and 10 μm and two pitches of patterns of Al were used to yield 8 area coverage ratio of 12.6, 19.6, 25.6, 34.9, 65.9, 74.4, 80.6 and 87.6%. The thickness of Al film 25nm to 200nm, patterned aluminum were fabricated on both glass and ITO glass substrates and aluminum induced crystallization was conducted at 600 ℃, 1Pa thermal annealing environment. Results showed that at α-Si/Al thickness ratio of 200 nm/25 nm silicon crystals can be formed on bare glass after annealing, with optimal crystallization of silicon at α-Si/Al thickness of 200 nm/100 nm. Whereas on ITO/glass α-Si/Al thickness ratio of 200 nm/50 nm silicon crystals can be observed. On bare glass with Si / Al thickness ratio of 200 nm/100 nm and aluminum area ratio from 74.4 to 87.4%, optical band gap of 1.2 eV was measured .
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Lin, Bo-Jhih, and 林柏志. "Novel Photo-Sensitizers for Dye-Sensitized Solar Cell Applications." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/22166834764583204340.
Full textAbstract:
碩士國立暨南國際大學
應用化學系
104
This thesis is focuse on the optimizing dye-sensitized solar cells of two series of novel photosensitizers. The first series of dyes (Me2N-PS1, Me2N-PS2, Me2N-PS3, Oct2N-PS1) are based on the published porphyrin dyes (LD14, LD16). For these PS dyes, we introduce thiophene derivative to substitute phenylethynyl (PE) as the bridge between the porphyrin core and the anchoring group. The result show a trend of Me2N-PS1 (6.76%) > Oct2N-PS1 (6.68%) > Me2N-PS2 (6.37%) > Me2N-PS3 (4.62%) This is in consistent with the reported PE1~PE4 dyes. In the second part, stable artificial chlorophyll, derivatives (LS-01, LS-11) were synthesized and used as photosensitizers. Remarkably, LS dyes show vivid colors (pink and blue) on TiO2. Phtotvoltaic measurements show a trend of efficiencies of LS dyes LS-11 (5.36%) > LS-01 (4.67%) > H2PE1 (2.06%).
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Chen, Chien-Ming, and 陳建銘. "Fabrication of CuGaSe2/Si heterostructures for solar-cell applications." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/62378035998612047542.
Full textAbstract:
碩士國立中山大學
材料與光電科學學系研究所
104
For the composition control and testing electric properties, polycrystalline CuGaSe2 (CGSe) films with near-stoichiometric compositions were deposited by three-source co-evaporation on glass without the substrate rotation. XRD analysis veried that the film is single phase with the chalcopyrite structure. From Cu-rich to Ga-rich regions for the film grown on a glass substrate,the film resistivities varied from 3.7x10-1 Ω‧cm to 7.4x104 Ω‧cm. Further experiments on the formation of Ohmic contacts onto CGSe films indicated that the remaining Cu-Se phase on the surface of Cu-rich CGSe could improve the contact properties for the film attached with Mo metal electrodes. Since the successful epitaxial growth should be demonstrated prior to device fabrication, Cu-rich CGSe(p-type CGSe) films were grown on (100) n-type Si wafers.XRD analysis reveal that the c-axis of tetragonal unit cell aligned parallel to the substrate surface to lower the strain energy and thus leaded to the formation of orientation domain structure. For the films grown at 550℃, the XRD peak of CGSe was broden and asymmetric indicating an interduffusion at the CGSe/Si interface. Auger depth profiling showed that a conderable amount of Si was diffused into CGSe. Considering in a Cu-rich CGSe that Si might incorporate into the lattice site of Ga and became as a donor, which could compensate the acceptor in p-type CGSe. This would seriously degrade the junction properties of p-CGSe/n-Si device structure. It is strongly suggested that a low-temperature process such as photo-assited MBE should be employed for the film growth. Keywords:Molecular beam deposition,orientation domain structure,CuGaSe2 epitaxy, CuGaSe2/Si heterojunction solar cell