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Thin Film Solar Cells From Earth Abundant Materials

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Thin Film Solar Cells From Earth Abundant Materials

Thin Film Solar Cells From Earth Abundant Materials Book
Author : Subba Ramaiah Kodigala
Publisher : Newnes
Release : 2013-11-14
ISBN : 0123971829
Language : En, Es, Fr & De

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Book Description :

The fundamental concept of the book is to explain how to make thin film solar cells from the abundant solar energy materials by low cost. The proper and optimized growth conditions are very essential while sandwiching thin films to make solar cell otherwise secondary phases play a role to undermine the working function of solar cells. The book illustrates growth and characterization of Cu2ZnSn(S1-xSex)4 thin film absorbers and their solar cells. The fabrication process of absorber layers by either vacuum or non-vacuum process is readily elaborated in the book, which helps for further development of cells. The characterization analyses such as XPS, XRD, SEM, AFM etc., lead to tailor the physical properties of the absorber layers to fit well for the solar cells. The role of secondary phases such as ZnS, Cu2-xS,SnS etc., which are determined by XPS, XRD or Raman, in the absorber layers is promptly discussed. The optical spectroscopy analysis, which finds band gap, optical constants of the films, is mentioned in the book. The electrical properties of the absorbers deal the influence of substrates, growth temperature, impurities, secondary phases etc. The low temperature I-V and C-V measurements of Cu2ZnSn(S1-xSex)4 thin film solar cells are clearly described. The solar cell parameters such as efficiency, fill factor, series resistance, parallel resistance provide handful information to understand the mechanism of physics of thin film solar cells in the book. The band structure, which supports to adjust interface states at the p-n junction of the solar cells is given. On the other hand the role of window layers with the solar cells is discussed. The simulation of theoretical efficiency of Cu2ZnSn(S1-xSex)4 thin film solar cells explains how much efficiency can be experimentally extracted from the cells. One of the first books exploring how to conduct research on thin film solar cells, including reducing costs Detailed instructions on conducting research

Thin Film Solar Cells Using Earth Abundant Materials

Thin Film Solar Cells Using Earth Abundant Materials Book
Author : Parag S. Vasekar,Tara P. Dhakal
Publisher : Unknown
Release : 2013
ISBN : 9789535110033
Language : En, Es, Fr & De

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Book Description :

Download Thin Film Solar Cells Using Earth Abundant Materials book written by Parag S. Vasekar,Tara P. Dhakal, available in PDF, EPUB, and Kindle, or read full book online anywhere and anytime. Compatible with any devices.

Copper Zinc Tin Sulfide Based Thin Film Solar Cells

Copper Zinc Tin Sulfide Based Thin Film Solar Cells Book
Author : Kentaro Ito
Publisher : John Wiley & Sons
Release : 2015-02-23
ISBN : 111843787X
Language : En, Es, Fr & De

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Book Description :

Beginning with an overview and historical background of Copper Zinc Tin Sulphide (CZTS) technology, subsequent chapters cover properties of CZTS thin films, different preparation methods of CZTS thin films, a comparative study of CZTS and CIGS solar cell, computational approach, and future applications of CZTS thin film solar modules to both ground–mount and rooftop installation. The semiconducting compound (CZTS) is made up earth–abundant, low–cost and non–toxic elements, which make it an ideal candidate to replace Cu(In,Ga)Se2 (CIGS) and CdTe solar cells which face material scarcity and toxicity issues. The device performance of CZTS–based thin film solar cells has been steadily improving over the past 20 years, and they have now reached near commercial efficiency levels (10%). These achievements prove that CZTS–based solar cells have the potential to be used for large–scale deployment of photovoltaics. With contributions from leading researchers from academia and industry, many of these authors have contributed to the improvement of its efficiency, and have rich experience in preparing a variety of semiconducting thin films for solar cells.

Fabrication and Characterization of Low Cost Solar Cells based on Earth Abundant Materials for Sustainable Photovoltaics

Fabrication and Characterization of Low Cost Solar Cells based on Earth Abundant Materials for Sustainable Photovoltaics Book
Author : Mahmoud Abdelfatah
Publisher : Cuvillier Verlag
Release : 2016-07-08
ISBN : 3736982968
Language : En, Es, Fr & De

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Book Description :

The low cost and low temperature electrochemical deposition technique was employed to grow Cu2O thin films and ZnO:Al thin films were deposited by d.c. magnetron sputtering in order to fabricate solar cells. The potentiostatic and galvanostatic electrodeposition modes were used to deposit the Cu2O thin films. Raman spectra of thin films have shown characteristic frequencies of crystalline Cu2O. The contact between Cu2O and Au is found to be an Ohmic contact. The devices grown by a potentiostatic mode have higher efficiency than those grown by a galvanostatic mode. The optimum thickness of Cu2O thin films as an absorber layer in solar cells. was found to be around 3 µm respect to a high efficiency. Flexible and light weight solar cell was fabricated on plastic substrate.

Development of Earth abundant Materials and Low cost Processes for Solar Cells

Development of Earth abundant Materials and Low cost Processes for Solar Cells Book
Author : Chih-Liang Wang
Publisher : Unknown
Release : 2014
ISBN : 0987650XXX
Language : En, Es, Fr & De

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Book Description :

The goal of renewable solar energy research is to develop low-cost, high-efficiency photovoltaic technologies. However, with the growing deployment of solar cells, approaching the terawatt scale, absorber materials reliant upon rare or unfriendly elements become a crucial issue. Thus, the primary objective of this dissertation is the development of a low-cost fabrication method for (i) thin-film solar cells and (ii) dye-sensitized solar cells using earth-abundant materials. In thin-film solar cells, the kesterite Cu2ZnSnS4 with earth abundant elements is used as an absorber layer. It possesses a high absorption coefficient, direct band gap, and good long-term stability compared to the traditional CdTe and Cu(In,Ga)(S,Se)2 (CIGS) absorber layers. A facile hot-injection approach for synthesizing Cu2ZnSn(S,Se)4 nanocrystals with varied Se to (S+Se) ratio is developed to systematically investigate the role of Se in Cu2ZnSn(S,Se)4 nanocrystals and the evolution of Cu2ZnSn(S,Se)4 nanocrystals to Cu2ZnSn(S,Se)4 film during the sulfurization step to address the problems associated with its narrow compositional window and the loss of Sn during heat treatment. Additionally, the existing substrate-type device configuration for these solar cells uses a molybdenum (Mo) back contact, which suffers from serious disadvantages like the (i) presence of a Schottky barrier at the Mo/Cu2ZnSn(S,Se)4 interface and (ii) decomposition of Cu2ZnSn(S,Se)4 at the Mo interface. Accordingly, a low-cost and Mo-free superstrate-type device configuration of Au/Cu2ZnSn(S,Se)4/CdS/TiO2/ITO/glass is developed to evaluate the conversion efficiency and to avoid the occurrence of a Schottky barrier at the interface and potential decomposition pathways induced by the formation of Mo(S,Se)2. Furthermore, with the addition of ethyl cellulose, the loss of Sn associated with the conversion of CZTSe to CZTSSe during the grain growth process is mitigated, leading to an increase in the conversion efficiency compared to that of the precursor film without using ethyl cellulose. Such an improvement can provide insight into the grain growth of CZTSSe during the sulfurization process and thereby enhance the feasibility of sustainable, high efficiency CZTSSe solar devices. The excellent characteristics of dye-sensitized solar cells (DSSCs) with short energy-payback time, simple assembly, and eco-friendly features make them a potential option to utilize solar energy. Accordingly, a facile, low-cost, template-free route for TiO2 hollow submicrospheres embedded with SnO2 nanobeans is developed for use as a versatile scattering layer in DSSCs. Our designed structure simultaneously promotes dye adsorption, light harvesting, and electron transport, leading to a 28 % improvement in the conversion efficiency as compared with the film-based SnO2. In addition, a naturally-derived carbonaceous material as a Pt-free counter electrode for DSSCs is also developed for the first time: carbonized sucrose-coated eggshell membrane (CSEM). It is found that the carbonized sucrose-coated eggshell membranes consist of unique micropores of less than 2 nm, which effectively catalyze the triiodide into iodide in the light-electricity conversion process, leading to an improvement in the V [subscript oc] and a competitive efficiency as compared to that of a DSSC with a traditional Pt-based counter electrode.

Earth Abundant Materials for Solar Cells

Earth Abundant Materials for Solar Cells Book
Author : Sadao Adachi
Publisher : John Wiley & Sons
Release : 2015-10-28
ISBN : 1119052831
Language : En, Es, Fr & De

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Book Description :

Systematically describes the physical and materials properties of copper-based quaternary chalcogenide semiconductor materials, enabling their potential for photovoltaic device applications. Intended for scientists and engineers, in particular, in the fields of multinary semiconductor physics and a variety of photovoltaic and optoelectronic devices.

Earth Abundant Materials for Solar Cells

Earth Abundant Materials for Solar Cells Book
Author : Sadao Adachi
Publisher : John Wiley & Sons
Release : 2015-10-28
ISBN : 1119052785
Language : En, Es, Fr & De

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Book Description :

Systematically describes the physical and materials properties of copper-based quaternary chalcogenide semiconductor materials, enabling their potential for photovoltaic device applications. Intended for scientists and engineers, in particular, in the fields of multinary semiconductor physics and a variety of photovoltaic and optoelectronic devices.

Development of Earth Abundant Tin II Sulfide Thin Film Solar Cells by Vapor Deposition

Development of Earth Abundant Tin II  Sulfide Thin Film Solar Cells by Vapor Deposition Book
Author : Prasert Sinsermsuksakul
Publisher : Unknown
Release : 2013
ISBN : 0987650XXX
Language : En, Es, Fr & De

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Book Description :

To sustain future civilization, the development of alternative clean-energy technologies to replace fossil fuels has become one of the most crucial and challenging problems of the last few decades. The thin film solar cell is one of the major photovoltaic technologies that is promising for renewable energy. The current commercial thin film PV technologies are based on Cu(In,Ga)Se2 and CdTe. Despite their success in reducing the module cost below $1/Wp, these absorber materials face limitations due to their use of scarce (In and Te) and toxic (Cd) elements. One promising candidate for an alternative absorber material is tin monosulfide (SnS). Composed of cheap, non-toxic and earth-abundant elemental constituents, SnS can potentially provide inexpensive PV modules to reach the global energy demand in TW levels.

Thin Film Solar Cells with Earth Abundant Elements

Thin Film Solar Cells with Earth Abundant Elements Book
Author : Yue Yu
Publisher : Unknown
Release : 2017
ISBN : 0987650XXX
Language : En, Es, Fr & De

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Book Description :

The world energy consumption has increased rigorously in recent years due to the rapid economic development and the massive global population expansion. Today the world energy supply relies heavily on fossil fuels, known as non-renewable energy resources, which have limited reserves on Earth and do not form or replenish in a short period of time. Burning fossil fuels not only brings environmental pollutions but also results in carbon dioxide and other greenhouse gases, which are to blame for global warming. Therefore, to build a more sustainable and greener future, we have to develop alternative renewable energy resources. Photovoltaic (PV) cell, also commonly known as solar cell, is a very promising renewable energy technology. Here in this dissertation, we have studied two emerging PV materials with earth abundant elements, i.e. copper zinc tin sulfide (CZTS) and organic-inorganic hybrid halide perovskite. Having earth abundant elements means that the raw materials have rich reserves on Earth and the costs are relatively low. It also means that the materials have the potential capability to be produced in large scales in industry. We first explored two different deposition methods for preparing CZTS thin films. In the first method, the CZTS was fabricated by a solution based method with diethyl sulfoxide (DMSO) as the solvent and the effect of spin speed on the properties of CZTS thin films was studied. The results indicated that a higher spin speed was more favorable for attaining a more densely packed and pinhole-free film while no crystallographic differences were observed. In the second method, CZTS was fabricated using sputtered metal precursors followed by a closed-space sulfurization (CSS) technique, which had high manufacturing compatibility and could be applied in industry. After exploring different sulfurization conditions, including temperatures and time, the champion cell was obtained at 590oC for 30min, with a maximum power conversion efficiency (PCE) of 5.2%. We then explored three different organic-inorganic hybrid halide perovskite materials for solar cell applications. The first perovskite material is methylammonium tin triiodide (MASnI3, bandgap ~1.3 eV). It was fabricated by a hybrid thermal evaporation. The as-deposited MASnI3 thin films exhibit smooth surfaces, uniform coverage across the entire substrate, and strong crystallographic preferred orientation along the 100 direction. Our results demonstrate the potential capability of the hybrid evaporation method for preparing high-quality MASnI3 perovskite thin films which can be used to fabricate efficient lead (Pb)-free perovskite solar cells (PVSCs). The second perovskite material is mixed-cation (formamidinium and cesium) lead iodide (FA0.8Cs0.2PbI3). We find that one of the main factors limiting the PCEs of FA0.8Cs0.2PbI3 PVSCs could be the small grain sizes, which leads to relatively short mean carrier lifetimes. We further find that adding a small amount of lead thiocyanate additive can enlarge the grain size of FA0.8Cs0.2PbI3 perovskite thin films and significantly increase the mean carrier lifetime. As a result, the average PCE of FA0.8Cs0.2PbI3 PVSCs increases from 16.18 ± 0.50 (13.45 ± 0.78)% to 18.16 ± 0.54 (16.86 ± 0.63)% when measured under reverse (forward) voltage scans. The best-performing FA0.8Cs0.2PbI3 PVSC registers a PCE of 19.57 (18.12) % when measured under a reverse (forward) voltage scan. The third perovskite material is FA0.8Cs0.2Pb(I0.7Br0.3)3 (bandgap ~1.75 eV). We find that the cooperation of lead thiocyanate additive and a solvent annealing process can effectively increase the grain size of the perovskite thin films while avoiding the undesired excess lead iodide formation. As a result, the average grain size of the FA0.8Cs0.2Pb(I0.7Br0.3)3 perovskite thin films increases from 66 ± 24 nm to 1036 ± 111 nm and the mean carrier lifetime shows a more than 3-fold increase, from 330 ns to over 1000 ns. As a result, the average open-circuit voltage (Voc) of FA0.8Cs0.2Pb(I0.7Br0.3)3 PVSCs increases by 80 (70) mV and the average PCE increases from 13.44 ± 0.48 (11.75 ± 0.34)% to 17.68 ± 0.36 (15.58 ± 0.55)% when measured under reverse (forward) voltage scans. The best-performing wide-bandgap (~1.75 eV) PVSC registers a stabilized PCE of 17.18%, demonstrating its suitability for top cell applications in all-perovskite tandem solar cells.

Optoelectronic Modeling and Optimization of Graded bandgap Thin film Solar Cells

Optoelectronic Modeling and Optimization of Graded bandgap Thin film Solar Cells Book
Author : Faiz Ahmad
Publisher : Unknown
Release : 2020
ISBN : 0987650XXX
Language : En, Es, Fr & De

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Book Description :

Crystalline-silicon (c-Si) photovoltaic solar cells are increasingly taking over the energy production sector nowadays. Even in comparison to coal-fired and nuclear plants for generation of electricity, the cost of harnessing solar energy by photovoltaic means has gone down considerably during the last decade. However, microwatt-scale generators of electricity are needed for human progress to become effectively unconstrained by economics. Large-scale adoption of thin-film solar cells is necessary for that to happen. However, Earth-abundant materials with low toxicity and high power-conversion efficiency must be used for thin-film solar cells. A series of theoretical investigations were performed to tackle the problem of materials scarcity as well as to explore potential enhancements of power-conversion efficiency in thin-film solar cells by thinning the absorber layer, grading the bandgap in the absorber layer, and modifying the back end. Three different types of thin-film solar cells were considered: CIGS, CZTSSe, and AlGaAs. The bandgap of the absorber layer was varied either sinusoidally or linearly. The thickness of the absorber layer was varied from 100 nm to 2200 nm. Back-end modifications incorporating a periodically corrugated backreflector and a back-surface passivation layer were considered as well. A coupled optoelectronic model was used along with the differential evolution algorithm to maximize the efficiency in relation to geometric and bandgap-grading parameters. Furthermore, as colored solar cells can promote large-scale adoption of rooftop solar cells, efficiency loss due to color-rejection filters was estimated. The coupled optoelectronic optimization predicted that tailored bandgap grading could significantly improve efficiency for all three considered thin-film solar cells. For CIGS solar cells with a 2200-nm-thick absorber layer, an efficiency of 27.7% was predicted with a sinusoidally graded bandgap absorber layer along with back-end modifications in comparison to 22% efficiency achieved experimentally with a homogeneous CIGS absorber layer. An efficiency of 21.7% was predicted with sinusoidal grading of a 870-nm-thick absorber CZTSSe layer in comparison to 12.6% efficiency achieved experimentally with a 2200-nm-thick homogeneous CZTSSe layer. Similarly, an efficiency of 34.5% was predicted through optoelectronic optimization of AlGaAs solar cells with a sinusoidally graded bandgap absorber layer along with back-end modifications in comparison to 27.6% efficiency achieved experimentally with a homogeneous AlGaAs absorber layer. For colored thin-film solar cells, predictions of the efficiency loss varied from 10% to 20%, depending upon the percentage of rejection of incoming solar photons. Thus, optoelectronic optimization by bandgap grading and back-end modifications is more than enough to swallow efficiency reduction by the rejection of a certain percentage of incoming solar photons. Thus, the proposed design strategies provide a way to realize more efficient thin-film solar cells for the ubiquitous harnessing of solar energy at low-wattage levels, thereby promoting widespread adoption of thin-film solar cells as local energy sources. Also, cheap, small-scale off-grid generation of electricity will provide access to energy for populations living without electricity far from central grids in less-developed and developing regions of our planet, thus equalizing opportunity and decreasing income and gender gaps.

Improved Thin Film Solar Cells Made by Vapor Deposition of Earth Abundant Tin II Sulfide

Improved Thin Film Solar Cells Made by Vapor Deposition of Earth Abundant Tin II  Sulfide Book
Author : Leizhi Sun
Publisher : Unknown
Release : 2014
ISBN : 0987650XXX
Language : En, Es, Fr & De

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Book Description :

Tin(II) sulfide (SnS) is an earth-abundant, inexpensive, and non-toxic absorber material for thin film solar cells. SnS films are deposited by atomic layer deposition (ALD) through the reaction of a tin precursor, bis(N,N'-diisopropylacetamidinato)tin(II), and hydrogen sulfide. The SnS films demonstrate excellent surface morphology, crystal structure, phase purity, stoichiometry, elemental purity, and optical and electrical properties.

Alternative Substrates for Sustainable and Earth abundant Thin Film Photovoltaics

Alternative Substrates for Sustainable and Earth abundant Thin Film Photovoltaics Book
Author : Ignacio Becerril Romero
Publisher : Unknown
Release : 2019
ISBN : 0987650XXX
Language : En, Es, Fr & De

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Book Description :

"The development of sustainable energy sources with a high energy return on energy investment (EROI) that can substitute fossil fuels is a must in order to avoid the collapse of our current civilization. In this context, this work explores the feasibility of fabricating efficient Cu2ZnSn(Sx,Se1-x)4 (kesterite) solar cells on three strategic substrates: polyimide, ceramic and SnO2:F-coated soda-lime glass (SLG/FTO). These substrates present several advantages with respect to the standard SLG/Mo. Polyimide is compatible with roll-to-toll production processes and easily integrable in many applications thanks to its light weight and flexibility, ceramics have a direct application in building-integrated photovoltaics as solar tiles and the transparency of SLG/FTO enables advanced photovoltaic concepts like bifacial and tandem solar cells as well as the fabrication of semi-transparent devices. Their combination with a sustainable thin film photovoltaic technology based on Earth-abundant materials like kesterites has the potential of decreasing the energy fabrication cost and, thus, of increasing the EROI of photovoltaics through: 1) high throughput production, 2) integration and 3) advanced applications and functionality. However, these substrates also present several drawbacks. Alkalis, especially Na, are fundamental to achieve high efficiency devices but polyimide and ceramics are alkali-free materials. Likewise, FTO acts as a barrier for alkalis. In addition, polyimide presents a low thermal robustness that limits process temperatures below 500oC, ceramics are very rough and possess detrimental impurities and the use of FTO as back contact leads to a non-optimum p-kesterite/n-FTO interface. This work focuses on the implementation of specific strategies to adapt the kesterite solar cell fabrication process to the characteristics of the different substrates. A combination of alkaline doping and low-temperature annealings is studied for the fabrication of Cu2ZnSnSe4 solar cells on polyimide. While doping with NaF and KF is found to lead to critical improvements, working at low temperature is linked to the formation of SnSe2. This phase decreases the open-circuit voltage of the devices and is the main factor controlling their performance. Further experimentation leads to a 4.9% efficiency record device by combining NaF and Ge doping and a 480oC annealing. In the case of ceramic, vitreous enamels with controlled amounts of Na2O in their composition are used as surface smoothers, Na sources and impurity barriers, simultaneously. However, large amounts of Na2O in the enamel composition result in high densities of surface defects: undulations, pinholes and cracks. While undulations and pinholes are rather benign, cracks strongly deteriorate the back contact. In addition, the annealing time needs to be controlled to avoid the formation of SnSe2. Besides these issues, enamelled ceramic substrates are observed to behave similarly to SLG yielding a record Cu2ZnSnSe4 device with a 7.5% efficiency. Regarding SLG/FTO, the addition of transition metal oxides (TMOs) and/or Mo:Na nanolayers is studied as an approach to improve the back interface of the devices. Mo:Na is found to alleviate shunting and recombination issues and to protect FTO from degradation during annealing which leads to highly improved devices, especially for Cu2ZnSnS4. On the other hand, TMOs introduce a severe current blockage. However, the combination of the TiO2 and V2O5 with Mo:Na is observed to boost the beneficial effects of the latter in Cu2ZnSnSe4 and Cu2ZnSn(S,Se)4 devices. Although these multi-layered back interfaces exhibit a complex behaviour, this approach results in record efficiencies of 6.2%, 6.1% and 7.9% for Cu2ZnSnSe4, Cu2ZnSnS4 and Cu2ZnSn(S,Se)4 devices, respectively. These results represent the highest efficiencies ever reported for kesterite solar cells fabricated on polyimide, ceramic and transparent substrates and give proof of their large potential for sustainable kesterite-based photovoltaics." -- TDX.

Copper Zinc Tin Sulfide Thin Films for Photovoltaics

Copper Zinc Tin Sulfide Thin Films for Photovoltaics Book
Author : Jonathan J. Scragg
Publisher : Springer Science & Business Media
Release : 2011-09-01
ISBN : 9783642229190
Language : En, Es, Fr & De

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Book Description :

Jonathan Scragg documents his work on a very promising material suitable for use in solar cells. Copper Zinc Tin Sulfide (CZTS) is a low cost, earth-abundant material suitable for large scale deployment in photovoltaics. Jonathan pioneered and optimized a low cost route to this material involving electroplating of the three metals concerned, followed by rapid thermal processing (RTP) in sulfur vapour. His beautifully detailed RTP studies – combined with techniques such as XRD, EDX and Raman – reveal the complex relationships between composition, processing and photovoltaic performance. This exceptional thesis contributes to the development of clean, sustainable and alternative sources of energy

Development of Cu2ZnSnSe4 Based Thin Film Solar Cells by PVD and Chemical Based Processes

Development of Cu2ZnSnSe4 Based Thin Film Solar Cells by PVD and Chemical Based Processes Book
Author : Markus Neuschitzer
Publisher : Unknown
Release : 2016
ISBN : 0987650XXX
Language : En, Es, Fr & De

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Book Description :

Nowadays mono- and multicrystalline silicon have the highest market share of all PV technologies but thin film solar cells based on CdTe or Cu(In, Ga)Se2 (CIGS) absorbers recently show promising high power conversion efficiency values and due to their short energy payback time, minimal use of high purity material and low cost, they attract more and more attention. However, one concern of thin film PV based on CdTe or CIGS is the use of scare elements like tellurium or indium and gallium which could become a bottleneck if the technology wants to scale up to the terawatt level. Therefore, there is a high interest to replace these scare elements by more abundant ones and find suitable earth abundant photovoltaic absorbers. Cu2ZnSnSe4 (CZTSe) or Cu2ZnSnS4 (CZTS) and its sulphur-selenide solid solution are promising candidates to replace CIGS as absorber material due to its composition of more earth abundant elements. In literature CZTSe and CZTS are referred to as kesterite due to its crystal structure. However, there is still a large gap between power conversion efficiencies of solar cells based on kesterite absorber material and more established thin film solar cells, thus intensive research is still necessary to close this gap. The main goal of this thesis was to develop and optimize heterostructure solar cells based on Cu2ZnSnSe4 absorbers, by cost effective physical vapour deposition (PVD) and chemical based processes. Special focus is put on an improved understanding of the influence of the surface properties of kesterite absorbers on device performance and furthermore to optimize the front interface, i.e. buffer layer as well as the kesterite absorber layer itself. A detailed study investigating the influence of the surface chemistry on device performance is presented. After a chemical etching to remove unwanted ZnSe secondary phases formed during CZTSe absorber synthesis a low temperature post deposition annealing at 200ðC of the full solar cell is necessary to improve device efficiencies from below 3% to over 8%. X-ray photoelectron spectroscopy (XPS) surface analysis showed that this post deposition annealing promotes the diffusion of Zn towards the surface and Cu towards the bulk resulting in a Zn enriched and Cu depleted surface region, which is crucial for high device performance. Additionally experimental surface treatments confirm the necessity of a Cu-poor and Zn-rich surface and the reason for this beneficial surface composition are discussed in detail. Furthermore, the CdS buffer layer which is typically used in kesterite based heterostructures solar cells was optimized and allowed improvements in device performance of 1% absolute. This optimization was further extended to Cd-free ZnS(O, OH) buffer layer. Efficiencies close to that of CdS reference solar cells could be achieved using optimized ZnS(O, OH) buffer layer. Additionally to the front interface optimization, a Ge assisted crystallization process for nanocrystalline CZTSe precursors was developed which largely increase grain growth and boost open circuit voltages (Voc) to promising high values due to the elimination of deep defects. Since the low Voc values is identified of one of the main bottlenecks of kesterite technology, the improvements achieved are highly promising and give important insight for further possible optimizations.

Study of Earth Abundant TCO and Absorber Materials for Photovoltaic Applications

Study of Earth Abundant TCO and Absorber Materials for Photovoltaic Applications Book
Author : Tejas Prabhakar
Publisher : Unknown
Release : 2013
ISBN : 0987650XXX
Language : En, Es, Fr & De

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Book Description :

In order to make photovoltaic power generation a sustainable venture, it is necessary to use cost-effective materials in the manufacture of solar cells. In this regard, AZO (Aluminum doped Zinc Oxide) and CZTS (Copper Zinc Tin Sulfide) have been studied for their application in thin film solar cells. While AZO is a transparent conducting oxide, CZTS is a photovoltaic absorber. Both AZO and CZTS consist of earth abundant elements and are non-toxic in nature. Highly transparent and conductive AZO thin films were grown using RF sputtering. The influence of deposition parameters such as working pressure, RF power, substrate temperature and flow rate on the film characteristics was investigated. The as-grown films had a high degree of preferred orientation along the (002) direction which enhanced at lower working pressures, higher RF powers and lower substrate temperatures. Williamson-Hall analysis on the films revealed that as the working pressure was increased, the nature of stress and strain gradually changed from being compressive to tensile. The fall in optical transmission of the films was a consequence of free carrier absorption resulting from enhanced carrier density due to incorporation of Al atoms or oxygen vacancies. The optical and electrical properties of the films were described well by the Burstein-Moss effect. CZTS absorber layers were grown using ultrasonic spray pyrolysis at a deposition temperature of 350 C and subsequently annealed in a sulfurization furnace. Measurements from XRD and Raman spectra confirmed the presence of pure single phase Cu2ZnSnS4 . Texture analysis of as-deposited and annealed CZTS films indicated that the (112) plane which is characteristic of the kesterite phase was preferred. The grain size increased from 50 nm to 100 nm on conducting post-deposition annealing. CZTS films with stoichiometric composition yielded a band gap of 1.5 eV, which is optimal for solar energy conversion. The variation of tin in the film changed its resistivity by several orders of magnitude and subsequently the tin free ternary chalcogenide Cu2ZnS2 having very low resistivity was obtained. By carefully optimization of concentrations of tin, zinc and copper, a zinc-rich/tin-rich/copper-poor composition was found to be most suitable for solar cell applications. Etching of CZTS films using KCN solution reduced their resistivity, possibly due to the elimination of binary copper sulfide phases. CZTS solar cells were fabricated both in the substrate and superstrate configurations.

Sulfide and Selenide Based Materials for Emerging Applications

Sulfide and Selenide Based Materials for Emerging Applications Book
Author : Goutam Kumar Dalapati,Terence Kin Shun Wong,Subrata Kundu,Amit Kumar Chakraborty,Siarhei Zhuk
Publisher : Elsevier
Release : 2022-06-15
ISBN : 9780323998604
Language : En, Es, Fr & De

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Book Description :

Sulfide and Selenide based Materials for Emerging Applications addresses a materials and device approach to the transition to low cost sustainable thin film photovoltaic devices and energy storage systems. It is divided into 5 parts. Part 1 surveys the recent technological developments in kesterite film. Different synthesis methods and optical properties of the kesterire are covered to design the kesterite film for energy harvesting and storage technology. Chapters in part 1 discuss the latest research on dopant incorporation into CZTS including the effect of dopants on optical, electrical and structural properties on the kesterite. In section 2, thin film solar cells with earth abundant materials are discussed. The application of doped CZTS for earth abundant thin film solar cells and novel device structures is covered. In addition, emerging sulphide semiconductors with promising potential in thin film photovoltaics/flexible devices will be covered. There is focus on the interface engineering at the back contact of CZTS thin film solar cells. The use of various ultrathin intermediate layers with the ability to block the diffusion and reaction of Mo with CZTS is discussed. Emphasis is on the blocking mechanism; the effect of the intermediate layer on the absorber layer and the photovoltaic properties of the CZTS device. Section 3, covers the sulfur and selenides based materials for thermos-electric application. Part 4 of this book is concerned with chalcogenide semiconductors with applications in electrochemical water splitting. Pyrite and kesterite semiconductors which are earth abundant and have emerged as a promising class of nanoscale electro-catalyst material for the splitting of water into hydrogen and oxygen. The most recent developments in kesterite and pyrite semiconductors for electrochemical water splitting are surveyed. Part 5 discusses recent developments of storage technologies including Li-S batteries, sulfide based super-capacitors, and hydrogen storage. This book will be a useful resource for those involved in green energy technology and decarbonization and is designed for a broad audience, from students to the experienced scientist. Discuss the emerging sulfide/selenide based thin film absorber materials and their deposition methods Previews device engineering techniques that have been developed to enhance the power conversion efficiency and lifetime of sulfide/selenide based thin film solar cells Provides an update on what low cost sulfide/selenide based electro-catalysts have become available and the comparison of their performance versus noble metal catalyts

Terawatt Solar Photovoltaics

Terawatt Solar Photovoltaics Book
Author : Meng Tao
Publisher : Springer Science & Business Media
Release : 2014-04-07
ISBN : 1447156439
Language : En, Es, Fr & De

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Book Description :

Solar energy will undoubtedly become a main source of energy in our life by the end of this century, but how big of a role will photovoltaics play in this new energy infrastructure? Besides cost and efficiency, there are other barriers for current solar cell technologies to become a noticeable source of energy in the future. Availability of raw materials, energy input, storage of solar electricity, and recycling of dead modules can all prevent or hinder a tangible impact by solar photovoltaics. This book is intended for readers with minimal technical background and aims to explore not only the fundamentals but also major issues in large-scale deployment of solar photovoltaics. Thought-provoking ideas to overcoming some of the barriers are discussed.

Contrasting the Material Chemistry of Cu2ZnSnSe4 and Cu2ZnSnS 4 x Sex

Contrasting the Material Chemistry of Cu2ZnSnSe4 and Cu2ZnSnS 4 x Sex Book
Author : Anonim
Publisher : Unknown
Release : 2016
ISBN : 0987650XXX
Language : En, Es, Fr & De

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Book Description :

Earth-abundant sustainable inorganic thin-film solar cells, independent of precious elements, pivot on a marginal material phase space targeting specific compounds. Advanced materials characterization efforts are necessary to expose the roles of microstructure, chemistry, and interfaces. Here, the earth-abundant solar cell device, Cu2ZnSnS(4-x)Sex, is reported, which shows a high abundance of secondary phases compared to similarly grown Cu2ZnSnSe4.

Scientists Identify New Family of Iron Based Absorber Materials for Solar Cells Fact Sheet NREL Highlights Science

Scientists Identify New Family of Iron Based Absorber Materials for Solar Cells  Fact Sheet   NREL Highlights  Science Book
Author : Anonim
Publisher : Unknown
Release : 2011
ISBN : 0987650XXX
Language : En, Es, Fr & De

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Book Description :

Use of Earth-abundant materials in solar absorber films is critical for expanding the reach of photovoltaic (PV) technologies. The use of Earth-abundant and inexpensive Fe in PV was proposed more than 25 years ago in the form of FeS2 pyrite - fool's gold. Unfortunately, the material has been plagued by performance problems that to this day are both persistent and not well understood. Researchers from the National Renewable Energy Laboratory (NREL) and Oregon State University, working collaboratively in the Center for Inverse Design, an Energy Frontier Research Center, have uncovered several new insights into the problems of FeS2. They have used these advances to propose and implement design rules that can be used to identify new Fe-containing materials that can circumvent the limitations of FeS2 pyrite. The team has identified that it is the unavoidable metallic secondary phases and surface defects coexisting near the FeS2 thin-film surfaces and grain boundaries that limit its open-circuit voltage, rather than the S vacancies in the bulk, which has long been commonly assumed. The materials Fe2SiS4 and Fe2GeS4 hold considerable promise as PV absorbers. The ternary Si compound is especially attractive, as it contains three of the more abundant low-cost elements available today. The band gap (E{sub g} = 1.5 eV) from both theory and experiment is higher than those of c-Si and FeS2, offering better absorption of the solar spectrum and potentially higher solar cell efficiencies. More importantly, these materials do not have metallic secondary phase problems as seen in FeS2. High calculated formation energies of donor-type defects are consistent with p-type carriers in thin films and are prospects for high open-circuit voltages in cells.

Nanoscale Surface and Interface Characterization of Earth Abundant Thin Film Solar Cells

Nanoscale Surface and Interface Characterization of Earth Abundant Thin Film Solar Cells Book
Author : Kasra Sardashti
Publisher : Unknown
Release : 2016
ISBN : 0987650XXX
Language : En, Es, Fr & De

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Book Description :

Thin-film kesterites have been explored as promising absorbers in future photovoltaic devices due to their earth-abundant and non-toxic constituents, which do not impose any future production limitations. However, the current record conversion efficiency of polycrystalline kesterite devices is 12.6%--i.e., at least 2.4% short of the efficiency threshold needed to make this material competitive with chalcogenide-based thin film technologies. This shortage in conversion efficiency has been in part ascribed to the large extent of carrier recombination by defects at the grain boundaries and contact/absorber interfaces. In this work, methods nanoscale compositional and electrical characterization of grain boundaries and contact/absorber interfaces in kesterite solar cells have been developed, using a unique combination of advanced nano-characterization tools including Auger Nanoprobe Microscopy (NanoAuger), Kelvin Probe Force Microscopy (KPFM) and Cryogenic Focused Ion Beam (Cryo-FIB). NanoAuger and KPFM measurements on high-performance CZTSSe thin film PV devices revealed that the presence of SnOx at the grain boundaries is essential to the high VOC. This passivation layer needs to be formed by an air anneal process performed after the film deposition. In contrast to the oxide at the grain boundary, oxide layer on the top surfaces of the grains has been found to be (Sn,Zn),O. A new cross-sectioning method via grazing angle of incidence Cryo-FIB milling, has been developed where smooth cross-sections with at least 10x scale expansion have been prepared. These surfaces were characterized for CIGSe monitor films confirming the presence of MoSe2 interlayer acting as a proper hole contact on the back surface.