This book will guide Photovoltaics researchers in a new way of thinking about harvesting light energy from all wavelengths of the solar spectrum. It closes the gap between general solar cells books and photovoltaics journal articles, by focusing on the latest developments in our understanding of solid-state device physics. The material presented is experimental and based on II-VI thin-film materials, mainly CdTe-based solar cells. The authors describe the use of new device design, based on multilayer graded bandgap configuration, using CdTe-based solar cells. The authors also explain how the photo-generated currents can be enhanced using multi-step charge carrier production. The possibility of fabricating these devices using low-cost and scalable electroplating is demonstrated. The value of electroplating for large area electronic devices such as PV solar panels, display devices and nano-technology devices are also demonstrated. By enabling new understanding of the engineering of electroplated semiconductor materials and providing an overview of the semiconductor physics and technology, this practical book is ideal to guide researchers, engineers, and manufacturers on future solar cell device designs and fabrications. Discusses in detail the processes of growths, treatments, solar cell device fabrication and solid state physics, improving readers’ understanding of fundamental solid state physics; Enables future improvements in CdTe-based device efficiency; Explains the significance of defects in deposited semiconductor materials and interfaces that affect the material properties and resulting device performance.

Green Sustainable Process for Chemical and Environmental Engineering and Science: Solid State Synthetic Methods cover recent advances made in the field of solid-state materials synthesis and its various applications. The book provides a brief introduction to the topic and the fundamental principles governing the various methods. Sustainable techniques and green processes development in solid-state chemistry are also highlighted. This book also provides a comprehensive literature on the industrial application using solid-state materials and solid-state devices. Overall, this book is intended to explore green solid-state techniques, eco-friendly materials involved in organic synthesis and real-time applications. - Provides a broad overview of solid-state chemistry - Outlines an eco-friendly solid-state synthesis of modern nanomaterials, organometallic, coordination compounds and pure organic - Gives a detailed account of solid-state chemistry, fundamentals, concepts, techniques and applications - Deliberates cutting-edge recent advances in industrial technologies involved in energy, environmental, medicinal and organic chemistry fields

Solar energy conversion plays a very important role in the rapid introduction of renewable energy, which is essential to meet future energy demands without further polluting the environment, but current solar panels based on silicon are expensive due to the cost of raw materials and high energy consumption during production. The way forward is to move towards thin-film solar cells using alternative materials and low-cost manufacturing methods. The photovoltaic community is actively researching thin-film solar cells based on amorphous silicon, cadmium telluride (CdTe), copper indium gallium diselenide (CIGS), and dye-sensitised and organic materials. However, progress has been slow due to a lack of proper understanding of the physics behind these devices. This book concentrates on the latest developments and attempts to improve our understanding of solid-state device physics. The material presented is mainly experimental and based on CdTe thin-film solar cells. The author extends these new findings to CIGS thin-film solar cells and presents a new device design based on graded bandgap multi-layer solar cells. This design has been experimentally tested using the well-researched GaAs/AlGaAs system, and initial devices have shown impressive device parameters. These devices are capable of absorbing all radiation (UV, visible and infra-red) within the solar spectrum and combine "impact ionisation" and "impurity photovoltaic" effects. The improved device understanding presented in this book should impact and guide future photovoltaic device development and low-cost thin-film solar panel manufacture. This new edition features an additional chapter besides exercises and their solutions, which will be useful for academics teaching in this field.

Thin-film solar cells are cheap and easy to manufacture but require improvements as their efficiencies are low compared to that of the commercially dominant crystalline-silicon solar cells. An optoelectronic model is formulated and implemented along with the differential evolution algorithm to assess the efficacy of grading the bandgap of the CIGS, CZTSSe, and AlGaAs photon-absorbing layer for optimizing the power-conversion efficiency of thin-film CIGS, CZTSSe, and AlGaAs solar cells, respectively, in the two-terminal single-junction format. Each thin-film solar cell is modeled as a photonic device as well as an electronic device. Solar cells with two (or more) photon-absorbing layers can also be handled using the optolelectronic model, whose results will stimulate experimental techniques for bandgap grading to enable ubiquitous small-scale harnessing of solar energy.

Graded bandgap solar cells were investigated that have a structure consisting of an N-type graded emitter and a base region with a constant bandgap. The emitter bandgap was 2.1 eV at the front surface and then graded to 1.74 eV at the N/P homojunction based on a 1.74 eV bandgap. The Aluminum Gallium Arsenide homojunction had a maximum value for internal photoresponse of 20% while the graded bandgap cell exhibited a peak value of 80%. Analyses of photoresponse data indicates the Aluminum Gallium Gallium Arsenide homojunctions are characterized by minority carrier diffusion lengths of only .03 micrometers in the emitter and 0.1 micrometers in the base. Thus, the effective field resulting from the graded emitter in the graded bandgap cell is necessary for an adequate photoresponse. Investigations of heteroface Gallium Arsenide solar cells continued with the purpose of building a data base for processing technology and characterization techniques. GaAs solar cells were fabricated with efficiencies over 17% using a P/N homojunction structure ans A1GaAs heteroface. Electro-optical characterization of GaAs cells has resulted in improved understanding of minority carrier properties, surface recombination velocity and current loss mechanisms. Keywords: Space power.

This book addresses the principles and materials for the development of next-generation solar cells for a sustainable global society Discusses the structures, working principles, and limitations of solar cells as well as the improvement methods of their power-conversion efficiency Introduces generations of cells as photovoltaic devices, including third-generation solar cells such as organic solar cells, quantum dots solar cells, and organic–inorganic hybrid solar cells Focuses on the emerging perovskite solar cells (PSCs) and deals with their cell configuration, transport materials, and fabrication processes in detail.

The objective of this work is to design, fabricate, characterize and analyze wide band gap gallium phosphide (GaP) solar cells which can be used in multi-junction solar cell systems as the top junction solar cell. The highest reported efficiency for a GaP solar cell has been achieved in this work. This solar cell has an open circuit voltage (Voc) of 1.53V, short circuit current density (Jsc) of 2.56mA/cm 2, fill factor (FF) of 74.06% and efficiency of 2.90% compared to the previous best reported efficiency of 1.17%. The wide band gap of GaP (2.26eV) makes it a very good candidate for the top junction solar cell in a multi-junction solar cell system. A wide band gap solar cell can increase the efficiency of the system by absorbing and converting the high energy photons more efficiently. A five-junction solar cell system that includes a GaP solar cell as the top junction has the potential to achieve over 50% efficiency. The novel system is based on the co-design of the optics, interconnects and solar cells that enables each individual solar cell to have separate electrical contacts. The separate contact design is important to the multi-junction system because it can eliminate the lattice and current match requirements. The absolute efficiency gain of using a GaP solar cell as the top junction in the five-junction solar cell system can be as high as 3.6%. In this thesis, the GaP solar cells have been designed, fabricated and improved using a systematic approach. High quality GaP epitaxial layers were grown on GaP substrates using liquid phase epitaxy (LPE). The layer quality was analyzed by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The baseline and the first generation GaP solar cells were fabricated using a p on n structure. The solar cells were analyzed using quantum efficiency and current-voltage measurement. Specific materials parameters were then improved using predictive models based on these results. The analysis identified that the diffusion length in the base (n -type) limited the performance. Accordingly, a second generation GaP solar cell was designed, fabricated and tested using an improved n on p structure. The second generation GaP solar cell demonstrated significant improvement. Four more generations of GaP solar cells have been designed and fabricated using the predictive model based on the second generation GaP solar cell's analysis. The four new generations of GaP solar cells focused on first increasing the emitter region diffusion length; second, further improvements in the base region diffusion length; third, the emitter thickness and; finally, the front surface passivation. Systematic improvements have been achieved from these four new generations of GaP solar cells. The sixth generation GaP solar cell with AlGaP front surface passivation has achieved the highest efficiency GaP solar cell to date. Optical analysis of the GaP as a transparent top solar cell in a five-junction solar cell system has been performed to determine the design rules for this solar cell to be used as a "transparent" top solar cell. A new five-junction solar cell system has been proposed based on this analysis. With improved epitaxial layers growth conditions and solar cell designs, a pathway to 12.6% efficiency GaP top solar cells is described in this work. The development of wide band gap solar cells will broaden the design space for multi-junction solar cells. This work demonstrates the design rules for wide bandgap solar cells. The result will be beneficial to the design of multi-junction solar cells and the improvement of the solar cell module conversion efficiency.