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.
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
A method for synthesizing a thin film of copper, zinc, tin, and a chalcogen species ('CZTCh' or 'CZTSS') with well-controlled properties. The method includes depositing a thin film of precursor materials, e.g., approximately stoichiometric amounts of copper (Cu), zinc (Zn), tin (Sn), and a chalcogen species (Ch). The method then involves re-crystallizing and grain growth at higher temperatures, e e.g., between about 725 and 925 degrees K, and annealing the precursor film at relatively lower temperatures, e.g., between 600 and 650 degrees K. The processing of the precursor film takes place in the presence of a quasi-equilibrium vapor, e.g., Sn and chalcogen species. The quasi-equilibrium vapor is used to maintain the precursor film in a quasi-equilibrium condition to reduce and even prevent decomposition of the CZTCh and is provided at a rate to balance desorption fluxes of Sn and chalcogens.
The increasing demand for electronic devices for private and industrial purposes lead designers and researchers to explore new electronic devices and circuits that can perform several tasks efficiently with low IC area and low power consumption. In addition, the increasing demand for portable devices intensifies the call from industry to design sensor elements, an efficient storage cell, and large capacity memory elements. Several industry-related issues have also forced a redesign of basic electronic components for certain specific applications. The researchers, designers, and students working in the area of electronic devices, circuits, and materials sometimesneed standard examples with certain specifications. This breakthrough work presents this knowledge of standard electronic device and circuit design analysis, including advanced technologies and materials. This outstanding new volume presents the basic concepts and fundamentals behind devices, circuits, and systems. It is a valuable reference for the veteran engineer and a learning tool for the student, the practicing engineer, or an engineer from another field crossing over into electrical engineering. It is a must-have for any library.
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.
Materials for type III solar cells have branched into a series of generic groups. These include organic ‘small molecule’ and polymer conjugated structures, fullerenes, quantum dots, copper indium gallium selenide nanocrystal films, dyes/TiO2 for Grätzel cells, hybrid organic/inorganic composites and perovskites. Whilst the power conversion efficiencies of organic solar cells are modest compared to other type III photovoltaic materials, plastic semiconductors provide a cheap route to manufacture through solution processing and offer flexible devices. However, other types of materials are proving to be compatible with this type of processing whilst providing higher device efficiencies. As a result, the field is experiencing healthy competition between technologies that is pushing progress at a fast rate. In particular, perovskite solar cells have emerged very recently as a highly disruptive technology with power conversion efficiencies now over 20%. Perovskite cells, however, still have to address stability and environmental issues. With such a diverse range of materials, it is timely to capture the different technologies into a single volume of work. This book will give a collective insight into the different roles that nanostructured materials play in type III solar cells. This will be an essential text for those working with any of the devices highlighted above, providing a fundamental understanding and appreciation of the potential and challenges associated with each of these technologies.
Photovoltaics Beyond Silicon: Innovative Materials, Sustainable Processing Technologies, and Novel Device Structures presents the latest innovations in materials, processing and devices to produce electricity via advanced, sustainable photovoltaics technologies. The book provides an overview of the novel materials and device architectures that have been developed to optimize energy conversion efficiencies and minimize environmental impacts. Advances in technologies for harnessing solar energy are extensively discussed, with topics including materials processing, device fabrication, sustainability of materials and manufacturing, and the current state-of-the-art. Contributions from leading international experts discuss the applications, challenges and future prospects of research in this increasingly vital field, providing a valuable resource for students and researchers working in this area. Presents a comprehensive overview and detailed discussion of solar energy technology options for sustainable energy conversion Provides an understanding of the environmental challenges to be overcome and discusses the importance of efficient materials utilization for clean energy Looks at how to design materials processing and optimize device fabrication, including metrics such as power-to-weight ratio, effectiveness at EOL compared to BOL, life-cycle analysis
