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Characterization Of Novel Materials For Thin Film Photovoltaics By Electron Paramagnetic Resonance And Optical Spectroscopic Methods
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Book Synopsis Characterization of Novel Materials for Thin Film Photovoltaics by Electron Paramagnetic Resonance and Optical Spectroscopic Methods by : Melissa Van Landeghem
Download or read book Characterization of Novel Materials for Thin Film Photovoltaics by Electron Paramagnetic Resonance and Optical Spectroscopic Methods written by Melissa Van Landeghem and published by . This book was released on 2020 with total page 168 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Advanced Characterization Techniques for Thin Film Solar Cells by : Uwe Rau
Download or read book Advanced Characterization Techniques for Thin Film Solar Cells written by Uwe Rau and published by John Wiley & Sons. This book was released on 2011-05-25 with total page 532 pages. Available in PDF, EPUB and Kindle. Book excerpt: Written by scientists from leading institutes in Germany, USA and Spain who use these techniques as the core of their scientific work and who have a precise idea of what is relevant for photovoltaic devices, this text contains concise and comprehensive lecture-like chapters on specific research methods. They focus on emerging, specialized techniques that are new to the field of photovoltaics yet have a proven relevance. However, since new methods need to be judged according to their implications for photovoltaic devices, a clear introductory chapter describes the basic physics of thin-film solar cells and modules, providing a guide to the specific advantages that are offered by each individual method. The choice of subjects is a representative cross-section of those methods enjoying a high degree of visibility in recent scientific literature. Furthermore, they deal with specific device-related topics and include a selection of material and surface/interface analysis methods that have recently proven their relevance. Finally, simulation techniques are presented that are used for ab-initio calculations of relevant semiconductors and for device simulations in 1D and 2D. For students in physics, solid state physicists, materials scientists, PhD students in material sciences, materials institutes, semiconductor physicists, and those working in the semiconductor industry, as well as being suitable as supplementary reading in related courses.
Book Synopsis Thin Films Photovoltaics by : Beddiaf Zaidi
Download or read book Thin Films Photovoltaics written by Beddiaf Zaidi and published by BoD – Books on Demand. This book was released on 2022-02-23 with total page 114 pages. Available in PDF, EPUB and Kindle. Book excerpt: Thin film photovoltaic-based solar modules produce power at a low cost per watt. They are ideal candidates for large-scale solar farms as well as building-integrated photovoltaic applications. They can generate consistent power, not only at elevated temperatures but also on cloudy, overcast days and at low sun angles.Thin film photovoltaics are second-generation solar cells produced by depositing one or more thin layers, or thin films, of photosensitive material on a suitable substrate such as glass, polymer, or metal. Thin film solar cells are based on various materials such as cadmium telluride (CdTe), copper indium gallium diselenide (CIGS), and amorphous thin film silicon (a-Si, TF-Si) are commercially used in several conventional and advanced technologies.
Book Synopsis Handbook of Thin Films, Five-Volume Set by : Hari Singh Nalwa
Download or read book Handbook of Thin Films, Five-Volume Set written by Hari Singh Nalwa and published by Academic Press. This book was released on 2001-10-29 with total page 661 pages. Available in PDF, EPUB and Kindle. Book excerpt: This five-volume handbook focuses on processing techniques, characterization methods, and physical properties of thin films (thin layers of insulating, conducting, or semiconductor material). The editor has composed five separate, thematic volumes on thin films of metals, semimetals, glasses, ceramics, alloys, organics, diamonds, graphites, porous materials, noncrystalline solids, supramolecules, polymers, copolymers, biopolymers, composites, blends, activated carbons, intermetallics, chalcogenides, dyes, pigments, nanostructured materials, biomaterials, inorganic/polymer composites, organoceramics, metallocenes, disordered systems, liquid crystals, quasicrystals, and layered structures. Thin films is a field of the utmost importance in today's materials science, electrical engineering and applied solid state physics; with both research and industrial applications in microelectronics, computer manufacturing, and physical devices. Advanced, high-performance computers, high-definition TV, digital camcorders, sensitive broadband imaging systems, flat-panel displays, robotic systems, and medical electronics and diagnostics are but a few examples of miniaturized device technologies that depend the utilization of thin film materials. The Handbook of Thin Films Materials is a comprehensive reference focusing on processing techniques, characterization methods, and physical properties of these thin film materials.
Book Synopsis Theory And Methods Of Photovoltaic Material Characterization: Optical And Electrical Measurement Techniques by : Ahrenkiel Richard K
Download or read book Theory And Methods Of Photovoltaic Material Characterization: Optical And Electrical Measurement Techniques written by Ahrenkiel Richard K and published by World Scientific. This book was released on 2019-02-27 with total page 328 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book provides an extensive review of the theory of transport and recombination properties in semiconductors. The emphasis is placed on electrical and optical techniques. There is a presentation of the latest experimental and theoretical techniques used to analyze minority-carrier lifetime. The relevant hardware and instrumentation are described. The newest techniques of lifetime mapping are presented. The issues are discussed relating to effects that mask carrier lifetime in certain device structures. The discrepancy between photoconductive and photoluminescence measurement results are analyzed.
Book Synopsis Polymer Blend Film for Photovoltaic Applications Optical Characterization and Solar Cell Performance by : Annie Ng
Download or read book Polymer Blend Film for Photovoltaic Applications Optical Characterization and Solar Cell Performance written by Annie Ng and published by . This book was released on 2017-01-26 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation, "Polymer Blend Film for Photovoltaic Applications Optical Characterization and Solar Cell Performance" by Annie, Ng, 吳玥, was obtained from The University of Hong Kong (Pokfulam, Hong Kong) and is being sold pursuant to Creative Commons: Attribution 3.0 Hong Kong License. The content of this dissertation has not been altered in any way. We have altered the formatting in order to facilitate the ease of printing and reading of the dissertation. All rights not granted by the above license are retained by the author. Abstract: 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. DOI: 10.5353/th_b5153702 Subjects: Conducting polymers Solar cells
Book Synopsis Spatially Resolved Characterization in Thin-Film Photovoltaics by : Matevž Bokalič
Download or read book Spatially Resolved Characterization in Thin-Film Photovoltaics written by Matevž Bokalič and published by Springer. This book was released on 2015-01-22 with total page 106 pages. Available in PDF, EPUB and Kindle. Book excerpt: The book is devoted to the spatial characterization of solar cells and PV modules. It is written both as a monograph as well as a succinct guide for the state-of-the-art spatial characterization techniques and approaches. Amongst the approaches discussed are visual imaging, electro- and photo-luminescence imaging, thermography, and light beam induced mapping techniques. Emphasis is given on the luminescence image acquisition and interpretation due to its great potential. Characterization techniques are accompanied by simulation tools. The contents are aimed at a readership of students and senior researchers in R&D as well as engineers in industry who are newcomers to the spatial characterization of either solar cells or PV modules. The concepts and approaches presented herein are based on but not limited to case studies of real thin-film PV devices. Key features: Review of spatially resolved characterization techniques and accompanying SPICE simulations in photovoltaics Use of spatially resolved characterization techniques and their combinations for the identification of inhomogeneities in small area CdTe and dye-sensitized solar cells Case studies of electroluminescence imaging of commercial PV modules (c-Si, CIGS, CdTe, a-Si, tandem and triple junction thin-film-Si) The contents are aimed at a readership of students and senior researchers in R&D as well as engineers in industry who are newcomers to the spatial characterization of either solar cells or PV modules. The concepts and approaches presented herein are based on but not limited to case studies of real thin-film PV devices. Key features: Review of spatially resolved characterization techniques and accompanying SPICE simulations in photovoltaics Use of spatially resolved characterization techniques and their combinations for the identification of inhomogeneities in small area CdTe and dye-sensitized solar cells Case studies of electroluminescence imaging of commercial PV modules (c-Si, CIGS, CdTe, a-Si, tandem and triple junction thin-film-Si)
Book Synopsis Semiconductor Materials for Solar Photovoltaic Cells by : M. Parans Paranthaman
Download or read book Semiconductor Materials for Solar Photovoltaic Cells written by M. Parans Paranthaman and published by Springer. This book was released on 2015-09-16 with total page 290 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book reviews the current status of semiconductor materials for conversion of sunlight to electricity, and highlights advances in both basic science and manufacturing. Photovoltaic (PV) solar electric technology will be a significant contributor to world energy supplies when reliable, efficient PV power products are manufactured in large volumes at low cost. Expert chapters cover the full range of semiconductor materials for solar-to-electricity conversion, from crystalline silicon and amorphous silicon to cadmium telluride, copper indium gallium sulfide selenides, dye sensitized solar cells, organic solar cells, and environmentally friendly copper zinc tin sulfide selenides. The latest methods for synthesis and characterization of solar cell materials are described, together with techniques for measuring solar cell efficiency. Semiconductor Materials for Solar Photovoltaic Cells presents the current state of the art as well as key details about future strategies to increase the efficiency and reduce costs, with particular focus on how to reduce the gap between laboratory scale efficiency and commercial module efficiency. This book will aid materials scientists and engineers in identifying research priorities to fulfill energy needs, and will also enable researchers to understand novel semiconductor materials that are emerging in the solar market. This integrated approach also gives science and engineering students a sense of the excitement and relevance of materials science in the development of novel semiconductor materials. · Provides a comprehensive introduction to solar PV cell materials · Reviews current and future status of solar cells with respect to cost and efficiency · Covers the full range of solar cell materials, from silicon and thin films to dye sensitized and organic solar cells · Offers an in-depth account of the semiconductor material strategies and directions for further research · Features detailed tables on the world leaders in efficiency demonstrations · Edited by scientists with experience in both research and industry
Book Synopsis Optical and Photovoltaic Properties of Copper Indium-gallium Diselenide Materials and Solar Cells by : Puruswottam Aryal
Download or read book Optical and Photovoltaic Properties of Copper Indium-gallium Diselenide Materials and Solar Cells written by Puruswottam Aryal and published by . This book was released on 2014 with total page 365 pages. Available in PDF, EPUB and Kindle. Book excerpt: The demand for clean and renewable energy sources in recent years has motivated research on the development of low cost, thin film photovoltaic devices. As a consequence, tools for the investigation and characterization of thin film photovoltaic component materials and devices, which can be implemented in real time as well as under in-line and off-line measurement conditions, are becoming increasingly important. Real time spectroscopic ellipsometry (RTSE) and ex-situ mapping spectroscopic ellipsometry (SE) are powerful characterization tools suitable for applications in the optimization of device performance and the evaluation of thin film photovoltaics technology scale-up from dot cell sizes in research laboratories to full module sizes in factories. These non-destructive optical probes implement multichannel spectroscopic detection for achieving high measurement speed, while simultaneously yielding high precision light-matter interaction parameters. The interaction parameters can be analyzed to obtain layer thicknesses as well as their optical properties from which material properties such as composition can be determined. The layer thicknesses and their optical properties in turn provide insights into the fraction of incident light absorbed in the active layer of the solar cell and also provide a basis for short-circuit current optimization through optical simulations. In this dissertation research, Cu(In, Ga)Se2 films with different Ga contents have been prepared by a one stage co-evaporation process. These films have been studied by spectroscopic ellipsometry (RTSE) in real time during their deposition, which has been performed at high temperature (570oC). After cooling the films to room temperature, in-situ SE measurements were undertaken in order to extract the dielectric functions of the thin film materials. An extended parameterization was established through the fitting of these dielectric functions to analytical functions, followed by the development of expressions in the free parameters that describe these analytical functions versus the Ga content. As a result of this parameterization, dielectric function spectra can be predicted for any desired composition. This capability was applied for the structural and compositional mapping of CIGS thin films and solar cells deposited over 10 cm × 10 cm substrate areas. Correlations of the deduced structural and compositional parameters with the corresponding device performance characteristics have yielded important insights with the potential to assist in the optimization of solar cell devices incorporating thin CIGS layers. In addition, a methodology of external quantum efficiency simulation (EQE) has been developed that relies on ex-situ spectroscopic ellipsometry analysis of complete thin film solar cells and so does not require free parameters. The simulations have been applied to CIGS and a-Si:H solar cells, based on the assumption that all photo-generated carriers within the active layers of these cells are collected without any recombination losses. Thus, it should be noted the predicted EQE is the maximum that the solar cell having the given structure can generate, and the difference between the predicted and measured EQE for the same device can provide insights into recombination losses in the device. Because the predicted EQE is based on specular interfaces, it can also be lower than the measured values due to light trapping caused by rough surfaces and interfaces. In another research area of interest for CIGS materials and solar cells, the role of the stage II/III substrate temperature (540oC - 640oC) in the deposition of the films by the three stage process has been studied, as has its effect on device performance, sodium diffusion, and grain size. Since standard soda-lime glass does not tolerate temperatures above 570oC due to glass softening, specially engineered high temperature soda-lime glass produced by Nippon Electric Glass Co., Japan was used as the substrate material in this study. It was found that the average device performance improves up to 620oC as a consequence of reduced shunting and improved diode quality factor which affect the fill factor of the device. At 640oC, however, these parameters have exhibited a wider distribution, and thus have yielded a lower average efficiency for the cells. SEM micrographs of these devices showed that the grain size first increased with increasing temperature up to 620oC, and then showed a bimodal distribution at 640oC. Finally, ex-situ mapping ellipsometry has been applied in the study of silver nanoparticle thin films prepared by the drop casting method. These films are important because of the plasmonic effects they exhibit. Such effects can be exploited by integrating the nanoparticle layers into solar cells in order to promote light trapping, and hence, increase the overall efficiency of the cells. A study of these films with mapping spectroscopic ellipsometry provides a means of determining thickness uniformity over large areas that is critical for scale-up of the deposition processes. The uniformity of other parameters of the films such as the plasmon resonance energy and its broadening are equally important to ensure maximum coupling of light into the solar cell absorber layer.
Download or read book Energy Research Abstracts written by and published by . This book was released on 1995 with total page 782 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Scientific and Technical Aerospace Reports by :
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1995 with total page 704 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Photovoltaic and Photoactive Materials by : Joseph M. Marshall
Download or read book Photovoltaic and Photoactive Materials written by Joseph M. Marshall and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 361 pages. Available in PDF, EPUB and Kindle. Book excerpt: The primary objective of this NATO Advanced Study Institute (ASI) was to present an up-to-date overview of various current areas of interest in the field of photovoltaic and related photoactive materials. This is a wide-ranging subject area, of significant commercial and environmental interest, and involves major contributions from the disciplines of physics, chemistry, materials, electrical and instrumentation engineering, commercial realisation etc. Therefore, we sought to adopt an inter disciplinary approach, bringing together recognised experts in the various fields while retaining a level of treatment accessible to those active in specific individual areas of research and development. The lecture programme commenced with overviews of the present relevance and historical development of the subject area, plus an introduction to various underlying physical principles of importance to the materials and devices to be addressed in later lectures. Building upon this, the ASI then progressed to more detailed aspects of the subject area. We were also fortunately able to obtain a contribution from Thierry Langlois d'Estaintot of the European Commission Directorate, describing present and future EC support for activities in this field. In addition, poster sessions were held throughout the meeting, to allow participants to present and discuss their current activities. These were supported by what proved to be very effective feedback sessions (special thanks to Martin Stutzmann), prior to which groups of participants enthusiastically met (often in the bar) to identify and agree topics of common interest.
Book Synopsis Structural Characterization of Photovoltaic Nanocrystals, Single Crystals, and Thin Film Semiconductors by : Erin Elizabeth Jedlicka
Download or read book Structural Characterization of Photovoltaic Nanocrystals, Single Crystals, and Thin Film Semiconductors written by Erin Elizabeth Jedlicka and published by . This book was released on 2021 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: According to the U.S. Energy Information Administration, solar and wind make up over two-thirds of the 39.7 giga-watts (GW) of new energy capacity added to the grid in 2021. In addition, wind turbine service technicians and solar panel installers are ranked number one and number three respectively on the U.S. Bureau of Labors "Fastest Growing Occupations for 2019-2029". However, currently solar panels require energy-consuming manufacturing processes, are limited to inflexible substrates, and only convert around 20-30% of light into electricity. Many new alternative materials for solar cells emerged with in the past few decades with low-cost solution processing, the ability to print onto flexible substrates, and the potential to convert higher percentages of light into electricity. However, most studies focus on the improvements in performance without studying the impact that changing processing conditions and adding dopants has on the vertical composition and crystalline structure of the material. Here, we study the structural characteristics of different photovoltaic materials to determine the impact of different processing methods and dopants. First, we investigate the vertical composition in solution processed photovoltaic semiconductor materials. While solution-processed solar cells offer a low-cost and less energy consuming manufacturing method, the processing materials and method highly impact the performance of the solar cell. In Chapter 2, we investigate how changes in processing photovoltaic thin-films impacts the film morphology and vertical composition of the film. We use glow discharge optical emission spectroscopy (GDOES) coupled with scanning electron microscopy (SEM) to analyze changes in film morphology. We look at three types of semiconductor materials: polymer/quantum dot blends, kesterite, and chalcopyrite. In polymer/quantum dot blends use GDOES to confirm the depth composition from a three-dimensional reconstruction using discrete algebraic reconstruction technique (DART) from scanning electron microscopy images. We discover that a post-deposition ligand exchange directly from the native quantum dot ligands to shorter, electrically conducting ligands results in damage to film causing cracks and voids. However, using a solution-based exchange to an intermediary ligand before a post-deposition ligand prevents damage to the film and results in better device performance. Next, we use GDOES to show that Ag-doping in kesterite films results in a more homogenous composition throughout the film depth and reduces the voids in the film. Finally, we discover that the selenization copper-rich under higher pressure allows results in films with fewer voids and Na-passivated defects. Overall, we see that processing conditions impact the vertical composition and can change the performance of photovoltaic materials. In addition to changes from processing conditions, changes in material properties can be induced by doping the material. In Chapter 3, we investigate how doping changes the structure of methylammonium lead tribromide (MAPbBr3) single crystals. We observe a shift in the structural phase transition temperature as a result of bismuth incorporation into the crystal structure. Using x-ray diffraction, we discover a contraction in the lattice constant with increase bismuth concentration. We compare the lattice contraction to the effects of applying external pressure to MAPbBr3 and observe a similar shift to lower temperatures for the phase transition. We use density functional theory (DFT) simulations and determine the likely defect species to be BiPb+. In our final chapter, we investigate the impacts of a remote outreach activity on student knowledge and attitudes towards science. We use pre/post-activity surveys to evaluate changes in student understanding of Next Generation Science Standards (NGSS) aligned content about the relationship between energy production and the environment. We also use 5-point Likert-scale surveys to measure student attitudes towards STEM/STEM careers. We use quantitative statistical analysis methods such as Welch’s t-test, Mann-Whitney U test, and Wilcoxon Signed Ranked test to determine the significance of changes between pre/post-activity surveys. We find an increase in the probability of students identifying wind, hydropower, and nuclear energy as renewable resources on the post-survey. Similarly, for non-renewable resources we find an increase in the probability that students identify fossil fuels, gas, and nuclear on the post-activity survey. We observe no changes in student attitudes towards STEM/STEM careers between pre/post survey. However, we determine that teachers over-estimated the changes in student attitudes from the outreach activity. We also observe an interesting result in the post-activity surveys with a higher mean response for “I enjoyed this [outreach] activity” and compared to the mean response for “I enjoy science and engineering activities”. This discrepancy in student attitudes should be further studied, however this provides insight in how we can improve student attitudes towards science and engineering activities.
Book Synopsis Electronic Characterisation of Earth‐Abundant Sulphides for Solar Photovoltaics by : Thomas James Whittles
Download or read book Electronic Characterisation of Earth‐Abundant Sulphides for Solar Photovoltaics written by Thomas James Whittles and published by Springer. This book was released on 2018-07-31 with total page 362 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book examines the electronic structure of earth-abundant and environmentally friendly materials for use as absorber layers within photovoltaic cells. The corroboration between high-quality photoemission measurements and density of states calculations yields valuable insights into why these materials have demonstrated poor device efficiencies in the vast literature cited. The book shows how the materials’ underlying electronic structures affect their properties, and how the band positions make them unsuitable for use with established solar cell technologies. After explaining these poor efficiencies, the book offers alternative window layer materials to improve the use of these absorbers. The power of photoemission and interpretation of the data in terms of factors generally overlooked in the literature, such as the materials’ oxidation and phase impurity, is demonstrated. Representing a unique reference guide, the book will be of considerable interest and value to members of the photoemission community engaged in solar cell research, and to a wider materials science audience as well.
Download or read book Solar Energy Update written by and published by . This book was released on 1981 with total page 688 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Polarized Resonance Synchronous Spectroscopy for Characterization of Materials’ Optical Properties by : Xiu Zhu Xu
Download or read book Polarized Resonance Synchronous Spectroscopy for Characterization of Materials’ Optical Properties written by Xiu Zhu Xu and published by . This book was released on 2020 with total page 143 pages. Available in PDF, EPUB and Kindle. Book excerpt: Optical spectroscopy is an essential tool for characterization of materials’ optical properties. Quantitatively understanding material absorption, scattering and emission properties is challenging with existing spectrometric and fluorometric techniques. The direct Polarized Resonance Synchronous Spectroscopy (PRS2) is a breakthrough to the existing spectroscopic techniques for differentiation and quantification of material absorption, scattering and emission properties including their light depolarizations and optical cross-sections. However, there are some limitations and unchecked assumptions in the direct PRS2 technique that need to be addressed during my PhD study. We first examined the effect of light scattering and absorption on their inner-filter-effect (IFE) and validated that sample UV-vis extinction can be approximated as absorption extinction for IFE correction in the PRS2 data processing due to the high sensitivity of PRS2 to light scattering. In the case where such approximation may produce large error, iteration PRS2 can be included to decompose the UV-vis extinction into absorption and scattering components. Compared to the direct PRS2 that must rely on several assumptions, the recent developed Bandwidth Varied PRS2 (BVPRS2) and Polarized Anti-Stokes’, On-resonance, Stokes’-shifted (PAOS) spectroscopic techniques are self-contained methods universally amenable to all kinds of fluorescent materials. BVPRS2 or PAOS is necessary for fluorescent materials that possess non-zero scattering depolarization and wavelength dependent fluorescence depolarization. Furthermore, BVPRS2 and PAOS prove that not only off-resonance fluorescence also contributes to the fluorescence signal detected in PRS2 measurement. BVPRS2 offers indirect observation that fluorescence intensity increases quadratically, while scattering signal increases linearly as wavelength bandwidth expands. More importantly, PAOS allows direct visualization of the contribution from anti-Stokes’-shifted fluorescence, ORF and Stokes’-shifted fluorescence in the detected signals, revealing the origins of the off-resonance contribution. Finally, it is illustrated that different PRS2 methods should be applied to different types of optical materials to ensure accuracy and efficiency. Direct PRS2 was readily used to study gold nanoparticles, which are light absorbers and scatterers. In contrast, PAOS-assisted PRS2 was performed on fluorescent quantum dots, which are simultaneously light absorbers, scatterers and emitters. The presented PRS2 methodology and the new insights acquired from the materials investigated should be of great significance to material design and characterization.
Book Synopsis Synthesis and Characterization of Functional Polymeric Materials for Use in Organic Photovoltaics by : Sarah Joy Moench
Download or read book Synthesis and Characterization of Functional Polymeric Materials for Use in Organic Photovoltaics written by Sarah Joy Moench and published by . This book was released on 2016 with total page 536 pages. Available in PDF, EPUB and Kindle. Book excerpt: Norbornene-type monomers with pendant oligothiophene donor and perylene diimide acceptor groups were synthesized and polymerized using ring-opening metathesis polymerization (ROMP) to yield donor and acceptor homopolymers. These semiconducting homopolymers were characterized by UV-Vis and fluorescence spectroscopy to determine absorbance maxima, emission and excitation profiles, optical bandgaps, molar absorbtivities, and quantum yields. The electrochemical behavior of the donor and acceptor materials was characterized by cyclic voltammetry to determine the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energy levels of the organic semiconductors. Donor-acceptor diblock copolymers were synthesized using ROMP. Fluorescence spectroscopy demonstrated increased donor emission quenching with decreasing block length. Random donor-acceptor copolymers demonstrated almost complete quenching of the donor emission, likely due to increased donor-acceptor interfaces for charge transfer. Electron paramagnetic resonance spectroscopy (EPR) confirmed the formation of persistent donor radical cations and acceptor radical anions in the block copolymers. Small-angle X-ray scattering (SAXS) demonstrated bulk microphase separation with domain sizes between 24-28 nm. Furthermore, the formation of crystalline structure within the ordered microdomains was also observed. All of these studies indicate that the designed materials may be useful as the active layer in organic photovoltaic applications. As a route to functional hybrid materials, block copolymers containing a donor-segment and a Lewis-basic oligoethylene glycol segment, for preferential ZnO nanoparticle growth, were synthesized by ROMP. Photophysical and electrochemical characterization demonstrated that the donor electronic properties were maintained upon incorporation into the copolymer. SAXS was used to demonstrate lamellar morphology in bulk films of the symmetric block copolymers. ZnO nanoparticles were synthesized and incorporated into composite thin films with the block copolymers. These composite films demonstrated high photoluminescence quenching, which increased upon thermal annealing, as a result of favorable charge transfer from the photo-excited donor to the ZnO nanoparticles. These studies demonstrate that improved morphology control and self-assembly can increase charge transfer in hybrid materials through increased interfacial area. As an alternative route to directed ZnO nanoparticle growth, a copolymer containing pendant dipicolylamine moieties was synthesized and characterized by photophysical and electrochemical methods.
