Download or read book Interfacial Engineering and Charge Carrier Dynamics in Extremely Thin Absorber Solar Cells written by Michael Edley and published by . This book was released on 2016 with total page 244 pages. Available in PDF, EPUB and Kindle. Book excerpt: Photovoltaic energy is a clean and renewable source of electricity; however, it faces resistance to widespread use due to cost. Nanostructuring decouples constraints related to light absorption and charge separation, potentially reducing cost by allowing a wider variety of processing techniques and materials to be used. However, the large interfacial areas also cause an increased dark current which negatively affects cell efficiency. This work focuses on extremely thin absorber (ETA) solar cells that used a ZnO nanowire array as a scaffold for an extremely thin CdSe absorber layer. Photoexcited electrons generated in the CdSe absorber are transferred to the ZnO layer, while photogenerated holes are transferred to the liquid electrolyte. The transfer of photoexcited carriers to their transport layer competes with bulk recombination in the absorber layer. After charge separation, transport of charge carriers to their respective contacts must occur faster than interfacial recombination for efficient collection. Charge separation and collection depend sensitively on the dimensions of the materials as well as their interfaces. We demonstrated that an optimal absorber thickness can balance light absorption and charge separation. By treating the ZnO/CdSe interface with a CdS buffer layer, we were able to improve the Voc and fill factor, increasing the ETA cell's efficiency from 0.53% to 1.34%, which is higher than that achievable using planar films of the same material. We have gained additional insight into designing ETA cells through the use of dynamic measurements. Ultrafast transient absorption spectroscopy revealed that characteristic times for electron injection from CdSe to ZnO are less than 1 ps. Electron injection is rapid compared to the 2 ns bulk lifetime in CdSe. Optoelectronic measurements such as transient photocurrent/photovoltage and electrochemical impedance spectroscopy were applied to study the processes of charge transport and interfacial recombination. With these techniques, the extension of the depletion layer from CdSe into ZnO was determined to be vital to suppression of interfacial recombination. However, depletion of the ZnO also restricted the effective diffusion core for electrons and slowed their transport. Thus, materials and geometries should be chosen to allow for a depletion layer that suppresses interfacial recombination without impeding electron transport to the point that it is detrimental to cell performance. Thin film solar cells are another promising technology that can reduce costs by relaxing material processing requirements. CuInxGa(1-x)Se (CIGS) is a well studied thin film solar cell material that has achieved good efficiencies of 22.6%. However, use of rare elements raise concerns over the use of CIGS for global power production. CuSbS2 shares chemistry with CuInSe2 and also presents desirable properties for thin film absorbers such as optimal band gap (1.5 eV), high absorption coefficient, and Earth-abundant and non-toxic elements. Despite the promise of CuSbS2, direct characterization of the material for solar cell application is scarce in the literature. CuSbS2 nanoplates were synthesized by a colloidal hot-injection method at 220 ℗ʻC in oleylamine. The CuSbS2 platelets synthesized for 30 minutes had dimensions of 300 nm by 400 nm with a thickness of 50 nm and were capped with the insulating oleylamine synthesis ligand. The oleylamine synthesis ligand provides control over nanocrystal growth but is detrimental to intercrystal charge transport that is necessary for optoelectronic device applications. Solid-state and solution phase ligand exchange of oleylamine with S2- were used to fabricate mesoporous films of CuSbS2 nanoplates for application in solar cells. Exchange of the synthesis ligand with S2- resulted in a two order of magnitude increase in 4-point probe conductivity. Photoexcited carrier lifetimes of 1.4 ns were measured by time-resolved terahertz spectroscopy, indicating potential for CuSbS2 as a solar cell absorber material.

Download or read book Charge Carrier Dynamics in Thin Film Solar Cells written by Christian Strothkämper and published by . This book was released on 2013 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Interfacial Engineering in Functional Materials for Dye Sensitized Solar Cells written by Alagarsamy Pandikumar and published by John Wiley & Sons. This book was released on 2019-10-30 with total page 288 pages. Available in PDF, EPUB and Kindle. Book excerpt: Offers an Interdisciplinary approach to the engineering of functional materials for efficient solar cell technology Written by a collection of experts in the field of solar cell technology, this book focuses on the engineering of a variety of functional materials for improving photoanode efficiency of dye-sensitized solar cells (DSSC). The first two chapters describe operation principles of DSSC, charge transfer dynamics, as well as challenges and solutions for improving DSSCs. The remaining chapters focus on interfacial engineering of functional materials at the photoanode surface to create greater output efficiency. Interfacial Engineering in Functional Materials for Dye-Sensitized Solar Cells begins by introducing readers to the history, configuration, components, and working principles of DSSC It then goes on to cover both nanoarchitectures and light scattering materials as photoanode. Function of compact (blocking) layer in the photoanode and of TiCl4 post-treatment in the photoanode are examined at next. Next two chapters look at photoanode function of doped semiconductors and binary semiconductor metal oxides. Other chapters consider nanocomposites, namely, plasmonic nanocomposites, carbon nanotube based nanocomposites, graphene based nanocomposites, and graphite carbon nitride based nanocompositesas photoanodes. The book: Provides comprehensive coverage of the fundamentals through the applications of DSSC Encompasses topics on various functional materials for DSSC technology Focuses on the novel design and application of materials in DSSC, to develop more efficient renewable energy sources Is useful for material scientists, engineers, physicists, and chemists interested in functional materials for the design of efficient solar cells Interfacial Engineering in Functional Materials for Dye-Sensitized Solar Cells will be of great benefit to graduate students, researchers and engineers, who work in the multi-disciplinary areas of material science, engineering, physics, and chemistry.

Download or read book Interface Engineering of Sb2S3 based Extremely Thin Absorber Solar Cells by Atomic Layer Deposition written by Pascal Büttner and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Extremely Thin Absorber Solar Cells written by Hasti Majidi and published by . This book was released on 2017 with total page 238 pages. Available in PDF, EPUB and Kindle. Book excerpt: A typical extremely thin absorber (ETA) cell comprises an extremely thin absorber layer at the interface between nanostructured, interpenetrating n-type and p-type semiconductors. Compared to planar photovoltaics, the large surface area of the nanostructured interface allows a thinner absorber layer to be used without sacrificing absorber volume. Photogenerated charges must be separated at the absorber interfaces before they recombine. Shorter distances for charge separation in ETA cells allow using materials with lower purity and higher defect densities, enabling use of inexpensive, solution-based processing methods. We report on electrodeposition of CdSe coatings onto ZnO nanowire arrays and determine the effect of processing conditions on material properties such as morphology and microstructure. We show that room-temperature electrodeposition enables growth of CdSe coatings that are uniform, and conformal with precise control over thickness and microstructure. Optimal range of current density was determined to achieve uniform and conformal coatings. Absorbers thinner than the charge collection length reduce bulk recombination and enhance charge separation at the interface. The charge collection length is directly related to the microstructure of the absorber coating. We report on the crystallite growth of electrodeposited CdSe coatings on ZnO nanowires during annealing. Both in situ transmission electron microscopy (TEM) and x-ray diffraction (XRD) reveal that the nanocrystal size increases from ~3 to ~10 nm upon annealing at 350 C for 1 h and then to more than 30 nm during another 1 h annealing at 400 C. Increased crystallite size, comparable to the coating thickness, shows a nearly two-fold improvement in power conversion efficiency upon annealing. In addition to the crystallinity of the coating, the absorber thickness affects the charge separation in ETA cells. Coatings that are too thin show poor light harvesting. However, too thick coatings show inefficient charge separation. We demonstrated optimum thickness of CdSe in the planar ETA cell. In addition, extremely thin coatings suffer from large interfacial recombination. Severe shunting in very thin absorbers is tackled by applying an ultra-thin (5 nm) coating of CdS on ZnO nanowires before CdSe electrodeposition. Interface engineering in ETA cells leads to five times improvement in the power conversion efficiency.

Download or read book Charge Carrier Dynamics in CuInS2 based Solar Cells written by Joris Petrus Theodorus Hofhuis and published by . This book was released on 2009 with total page 147 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Interface Engineering in Inorganic absorber Nanostructured Solar Cells written by Katherine Elizabeth Roelofs and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The focus of this work is variants on the dye-sensitized solar cell (DSSC) that employ inorganic materials as the light absorber, replacing the organic dye molecules used in DSSCs. Such DSSC-inspired devices are emerging technologies in the broader class of thin film solar cells, and include quantum-dot sensitized solar cells (QDSSCs) and perovskites solar cells (PSCs). Quantum-dot sensitized solar cells employ semiconductor nanocrystals, or quantum dots, as the light absorber. The band gap of quantum dots varies with size, allowing for a tunable absorption onset in these devices, among other benefits. PSCs, in which the absorber is CH3NH3PbI3, or variants thereof, with the perovskites crystal structure, first attracted attention in 2012 and have shown an unprecedented rise in efficiency to current record values of 20.1%. QDSSCs and PSCs can be fabricated completely from solution processed materials that can be low-purity, contrasting favorably with the industrial standard, silicon solar cells, which require expensively-processed, high-purity silicon. This tolerance to defects is partially due to the nanostructured design of some PSCs and all QDSSCs, in which a nanostructured bulk heterojunction is formed between the electron-transport material, the absorber, and the hole-transport material. However, the high interfacial areas involved in such designs leads to high rates of interfacial recombination, causing losses in photocurrent, and limiting device efficiency. In this work, I will present methods to reduce interfacial recombination in these inorganic-absorber nanostructured solar cells though surface modifications. In QDSSCs, these include growing ultra-thin insulating metal oxide films by atomic layer deposition (ALD) at the interface and controlling of the nucleation and growth of the inorganic absorber. These studies provide insight into the working mechanisms of QDSSCs, through a combination of the highly-controlled nature of ALD, where films can be grown a single atomic layer at a time and an interface can be atomically engineered, X-ray absorption measurements of interfacial geometric and electronic structure, and detailed studies of the resulting solar cell performance. I will also detail the use of ALD to grow entire material layers in perovskites solar cells, both ALD TiO2 as the electron-transport material, and ALD NiOx as the hole-transport material. Despite their high efficiencies, PSCs are unstable and rapidly degrade when exposed to moisture or excessive heat. The use of ultra-conformal inorganic layers grown by ALD to cap the perovskites absorber, instead of the currently-employed organic layers, has the potential to improve the stability, and thus efficiency, of perovskites solar cells.

Download or read book Functional materials with Charge Transfer Properties and Their Application in Photoelectric Devices written by Meng Zheng and published by Frontiers Media SA. This book was released on 2022-12-29 with total page 138 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Ultrafast Carrier Dynamics at P n Junction of Cu In Ga Se2 Based Solar Cells Measured by Optical Pump Terahertz Probe Spectroscopy written by Woo-Jung Lee and published by . This book was released on 2017 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Among other materials, the p-type Cu(In,Ga)Se2 (CIGS) alloy has attracted attention as the most efficient absorber in thin-film solar cells. The typical CIGS layer is deposited with a polycrystalline structure containing an amount of native defect states, which serve as carrier traps and recombination centers. These defect states in the CIGS layer can be easily changed after deposition of an n-type buffer layer, due to the formation of p-n junctions. To understand the influence of the p-n junction on these defect states, the behavior of photoexcited carriers, from the CIGS absorber to the buffer layer, is considered to be an important issue and is closely related to solar cell performance. In this study, we performed experiments to investigate the ultrafast carrier dynamics of CIGS-based solar cells, using optical pump terahertz (THz) probe (OPTP) spectroscopy, and demonstrated the correlation between solar cell performance and the behavior of photoexcited carrier dynamics.

Download or read book Halide Perovskites written by Tze-Chien Sum and published by John Wiley & Sons. This book was released on 2019-03-25 with total page 312 pages. Available in PDF, EPUB and Kindle. Book excerpt: Real insight from leading experts in the field into the causes of the unique photovoltaic performance of perovskite solar cells, describing the fundamentals of perovskite materials and device architectures. The authors cover materials research and development, device fabrication and engineering methodologies, as well as current knowledge extending beyond perovskite photovoltaics, such as the novel spin physics and multiferroic properties of this family of materials. Aimed at a better and clearer understanding of the latest developments in the hybrid perovskite field, this is a must-have for material scientists, chemists, physicists and engineers entering or already working in this booming field.

Download or read book Interfacial Engineering of Molecular Photovoltaics written by Steven Wade Shelton and published by . This book was released on 2014 with total page 52 pages. Available in PDF, EPUB and Kindle. Book excerpt: One of the most worthy pursuits in the field of organic solar cells is that of discovering ways to more effectively harvest charge generated by light absorption. The measure of the efficacy of this process is the external quantum efficiency (EQE). It is determined by the efficiency of incident light absorption, exciton diffusion, exciton splitting and charge transfer, and charge collection. Enhanced EQE can be realized by engineering interfaces between materials in the device to allow for smoother charge transfer throughout the extent of the device, which is usually between 10 and 200 nanometers. Improvements in charge transport are vitally important because the photogenerated excitons in electron donating polymers and small molecules typically only diffuse between 5 and 10 nanometers. These excitons must reach the interface between the electron donor and electron acceptor in order to be split so that the resulting electron and hole can be harvested at the cathode and anode, respectively. The aim of much of this dissertation is to describe a method by which the donor-acceptor interfacial area can be augmented using nanoimprint lithography, first with a single donor and then with multiple donors. Nanoimprint lithography is introduced as a simple embossing technique that can create features in a single component donor with dimensions as small as 20 nm. Solution-processable small molecules are of interest for their ease of synthesis and fabrication. I continue the discussion of nanoimprint lithography by offering candidates for a two-component donor combination. A two-component donor can extend the absorption range across a broader portion of the solar spectrum than just one donor to improve energy harvesting. After considering ways of optimizing the donor-acceptor interface, I describe the use of a charge selective layer for better charge transport and collection. When incorporated into a bilayer solar cell and an inverted solar cell, these two molecules markedly improve the energy conversion efficiency.

Download or read book Nanostructured Extremely Thin Absorber Solar Cells written by Eugen Zimmermann and published by . This book was released on 2013 with total page 78 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Modeling and Simulation of Charge Carrier Recombination Dynamics in Cu In Ga Se2 Thin Film Solar Cells written by José Fabio López Salas and published by . This book was released on 2018 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Solar cells with thin Cu(In,Ga)(S,Se)2 absorber films are well established in the photovoltaics market. They offer an advantage over other thin film technologies thanks to their lower content of elements with high toxicity or low earth abundance like Cd and Te. One approach to further improve the quality of production of these cells is to develop a method of material quality assessment during production that is fast, contactless and non-destructive. Time-resolved photoluminescence (TRPL) measurements offer all these characteristics. This work aims to establish the requirements to extract meaningful information about charge carrier recombination dynamics and solar cell performance parameters from TRPL measurements. To achieve this goal experiments and simulations are carried out. The material parameters are extracted from experiments and then built into the simulation model. Results from experiments also serve as the basis to verify the validity of this model. Parameter variations within the simulations function as one of the main methods in this work to gain deeper physical insight into the processes taking place during TRPL measurements. engl.

Download or read book Printable Mesoscopic Perovskite Solar Cells written by Hongwei Han and published by John Wiley & Sons. This book was released on 2023-06-07 with total page 309 pages. Available in PDF, EPUB and Kindle. Book excerpt: Printable Mesoscopic Perovskite Solar Cells A comprehensive exploration of printable perovskite solar cells and their potential for commercialization In Printable Mesoscopic Perovskite Solar Cells, a team of distinguished researchers delivers an accessible and incisive discussion of the principles, technologies, and fabrication processes associated with the manufacture and use of perovskite solar cells. The authors detail the properties, characterization methods, and technologies for halide perovskite materials and devices and explain printable processing technologies, mesoscopic anode and cathodes, and spacer layers for printable perovskite solar cells. In the book, you’ll find expansive discussions of the stability issues inherent in perovskite solar cells and explore the potential for scaling and commercializing the printing of perovskite solar cells, complete with real-world industry data. Readers will also find: A thorough introduction to the background and fundamentals of perovskite solar cells Comprehensive explorations of the characterization methods and technologies used with halide perovskite materials and devices Practical discussions of printable processing technologies for perovskite solar cells Fulsome treatments of the stability issues associated with perovskite solar cells and potential solutions for them Perfect for materials scientists, solid state physicists and chemists, and electronics engineers, Printable Mesoscopic Perovskite Solar Cells will also benefit surface chemists and physicists.

Download or read book Semiconductors Probed by Ultrafast Laser Spectroscopy written by R. R. Alfano and published by . This book was released on 1984 with total page 584 pages. Available in PDF, EPUB and Kindle. Book excerpt: Semiconductors Probed by Ultrafast Laser Spectroscopy, Volume II discusses the use of ultrafast laser spectroscopy in studying fast physics in semiconductors. It reviews progress on the experimental and theoretical understanding of ultrafast events that occur on a picosecond and nanosecond time scale. This volume discusses electronic relaxation in amorphous semiconductors and the physical mechanisms during and after the interaction of an intense laser pulse with a semiconductor. It also covers the relaxation of carriers in semiconductors; transient optical pulse propagation; and methods of tim ...

Download or read book Self assembled Monolayers of Thiols written by Abraham Ulman and published by . This book was released on 1998 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This work looks at thin films and self-assembled monolayers of thiols. It is aimed at researchers in chemistry, materials science, electrical engineering, biology and condensed matter physics.

Download or read book Thin Film Solar Cells written by Jef Poortmans and published by John Wiley & Sons. This book was released on 2006-10-16 with total page 504 pages. Available in PDF, EPUB and Kindle. Book excerpt: Thin-film solar cells are either emerging or about to emerge from the research laboratory to become commercially available devices finding practical various applications. Currently no textbook outlining the basic theoretical background, methods of fabrication and applications currently exist. Thus, this book aims to present for the first time an in-depth overview of this topic covering a broad range of thin-film solar cell technologies including both organic and inorganic materials, presented in a systematic fashion, by the scientific leaders in the respective domains. It covers a broad range of related topics, from physical principles to design, fabrication, characterization, and applications of novel photovoltaic devices.