Download or read book Spectroscopic Studies on the Impact of Defects in Hybrid Organic inorganic Perovskites on Charge Carrier Dynamics and Photovoltaic Device Performance written by Timothy Philippe Pollock and published by . This book was released on 2020 with total page 100 pages. Available in PDF, EPUB and Kindle. Book excerpt: Photovoltaic devices based on hybrid organic-inorganic perovskites have seen a historic rise in efficiency over the past decade. Relatively low cost of fabrication has allowed a wide range researchers to make meaningful contributions. This class of materials is fascinating in that it acts in some ways like well-known semiconductor systems, but exhibits certain key differences, which provides ample opportunity for future fundamental studies. The work described in this dissertation includes the spectroscopic characterization of charge carriers in methylammonium lead iodide and the use of this characterization, along with time-resolved spectroscopy, to better understand the influence of carrier dynamics on solar cell device performance. We observed that a decrease in device fill factor corresponded to an increase in trap state density and a change in the trapping rate constant, implying that the different film fabrication methods lead to a change in the nature of the trap states present in the film. Delving further into understanding the influence of trap states on the excited state dynamics in this system, we performed pump-push-probe spectroscopy and transient absorption spectroscopy with a variable wavelength sub-gap pump pulse to study both the energetics and kinetics of trapping processes in methylammonium lead iodide films. Here we utilized a low energy push pulse to delocalize trapped electrons back into the conduction band and then modeled the resulting recombination based on changes in trapped and free electron densities. From these studies, we were able to add experimental observations to the body of knowledge on the electronic structure of hybrid organic-inorganic perovskites. We also showed how dynamics in the early time periods (ps-ns) following photoexcitation can influence perovskite solar cell performance.

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 Hybrid Organic Inorganic Perovskites written by Li Wei and published by John Wiley & Sons. This book was released on 2020-10-19 with total page 290 pages. Available in PDF, EPUB and Kindle. Book excerpt: Hybrid organic-inorganic perovskites (HOIPs) have attracted substantial interest due to their chemical variability, structural diversity and favorable physical properties the past decade. This materials class encompasses other important families such as formates, azides, dicyanamides, cyanides and dicyanometallates. The book summarizes the chemical variability and structural diversity of all known hybrid organic-inorganic perovskites subclasses including halides, azides, formates, dicyanamides, cyanides and dicyanometallates. It also presents a comprehensive account of their intriguing physical properties, including photovoltaic, optoelectronic, dielectric, magnetic, ferroelectric, ferroelastic and multiferroic properties. Moreover, the current challenges and future opportunities in this exciting field are also been discussed. This timely book shows the readers a complete landscape of hybrid organic-inorganic pervoskites and associated multifuctionalities.

Download or read book Probing Local Heterogeneity in the Optoelectronic Properties of Organic inorganic Perovskites Using Fluorescence Microscopy written by Dane W. De Quilettes and published by . This book was released on 2017 with total page 221 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Halide Perovskites written by Tze-Chien Sum and published by John Wiley & Sons. This book was released on 2018-12-07 with total page 403 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 Optoelectronic Properties of CdSexTe1 x CuInSe2 and Perovskites for Photovoltaic Applications written by Niraj Shrestha and published by . This book was released on 2020 with total page 137 pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation includes the study of optoelectronic properties of CdSexTe1-x, CuInSe2 and perovskite thin films and solar cells utilizing photoluminescence (PL) spectroscopic methods. These materials have been widely used in photovoltaic (PV) applications. PL spectroscopy is a light-based, contactless, nondestructive tool to study the optoelectronic properties of semiconducting/photovoltaic materials. In general, PL spectroscopy has been utilized to study photogenerated charge carriers' processes such as radiative recombination events. Photogenerated carrier lifetime, a key parameter that correlates closely with achievable power conversion efficiency of solar cells, can be extracted by the application and analysis of PL spectroscopy. In addition, PL measurements performed at low temperatures are beneficial in identifying defect states in semiconductors, which contribute important fundamental information about a solar cell's performance. Application of CdSexTe1-x in CdTe based solar cells enhances the photocurrent, and hence the power conversion efficiency of CdTe based solar cells. Here, we explore how selenium content in CdSexTe1-x ternary alloys influences grain growth, crystal structure, and charge carrier dynamics. Enlarged average grain size and longer charge carrier lifetime are often beneficial to the power conversion efficiency of solar cells. Next, the presence of native defects in copper indium diselenide (CuInSe2, CIS), a widely used absorber layer in thin film solar cells because of its large absorption coefficient and controllable p-type conductivity, has been studied utilizing laser intensity- and temperature-dependent PL for thin films with two different Cu/In ratios. The detailed understanding of materials, sources of defect, and their optoelectronic behavior is essential to improve the performance of a solar cell. Our analysis reveals that the nature of defect emission in CIS is determined by its Cu/In ratio. In addition, a variety of studies on different compositions of perovskite crystalline thin films has been reported in this dissertation. Perovskites, due to their excellent optical and electrical properties, have been extensively studied in PV application. This dissertation discusses the impacts, observed for several additives (metal or lead thiocyanide), on grain growth as well as the charge carrier dynamics of organic-inorganic metal halide perovskites. Enhanced average grain size and increased charge carrier lifetime have been observed when specific additives were incorporated in the precursor solution during film preparation. Furthermore, the changes in the photophysics of perovskites that accompany its water-induced degradation have been studied. Without addressing such instability issues, the full potential of this promising PV technology cannot be realized. Two different metal halide perovskites (MAPbI3 and MAPbBr3) prepared by solution processes have been separately exposed to moisture at a relative humidity of 80 ± 5% (~25 mbar H2O at 300 K), and the photophysical changes of these perovskites have been explored utilizing in-situ PL/TRPL. Observed results indicate that MAPbI3 degrades in 4 stages while MAPbBr3 degrades in two stages when exposed to moisture within the time frame considered in this study. In addition, the presence of native defects together with temperature-dependent crystal phase transformation in MAPbI3 have been discussed. Temperature dependent PL along with laser intensity dependent PL reveal the existence of charge compensating defects in MAPbI3 perovskite thin films. Such defect states are formed when electrons from donor sites recombine with holes localized at acceptor sites, leading to the coexistence of positively charged donors and negatively charged acceptors. Charge compensating defects, when present in large concentration, halt the creation of free carriers in a semiconductor. The existence of such defects in MAPbI3, as revealed by our study, helps to explain the difficulty in increasing the equilibrium free carrier concentration of MAPbI3 by doping. Additionally, we observe the first order crystal phase transformation from orthorhombic to tetragonal in MAPbI3 found to occur at ~ 150 K. More interestingly, we observe that the incorporation of formamidinium cation (FA+) in MAPbI3 at proper concentration not only slows down the phase transition but also quenches the defect emission. To sum up, our findings of increased grain size and carrier lifetime obtained with the increase in Se content in CdSexTe1-x may aid in improving the performance of CdTe based solar cells. Similarly, dependence of the defect's type on Cu/In ratio in CIS films will help to enhance the power conversion efficiency of perovskite/CIS tandem solar cells. In addition, enlarged grain and longer charge carrier dynamics achieved with Pb(SCN)2 additive in perovskite help to make a high-quality absorber layer for perovskite solar cells. Furthermore, we believe that the perovskites' degradation mechanism together with their temperature dependent crystal phase transformation findings discussed in this dissertation show their great potential to be commercialized in the near future.

Download or read book Theoretical Modeling of Organohalide Perovskites for Photovoltaic Applications written by Giacomo Giorgi and published by CRC Press. This book was released on 2017-07-12 with total page 229 pages. Available in PDF, EPUB and Kindle. Book excerpt: Perovskites are a class of recently discovered crystals with a multitude of innovative applications. In particular, a lead role is played by organic-inorganic halide perovskites (OIHPs) in solar devices. In 2013 Science and Nature selected perovskite solar cells as one of the biggest scientific breakthroughs of that year. This book provides the first comprehensive account of theoretical aspects of perovskite solar cells, starting at an introductory level but covering the latest cutting-edge research. Theoretical Modeling of Organohalide Perovskites for Photovoltaic Applications aims to provide a theoretical standpoint on OIHPs and on their photovoltaic applications, with particular focus on the issues that are still limiting their usage in solar cells. This book explores the role that organic cations and defects play in the material properties of OIHPs and their effects on the final device, in addition to discussing the electric properties of OIHPs; the environmentally friendly alternatives to the use of lead in their structural and electronic properties; theoretical screening for OIHP-related material for solar-to-energy conversion; and the nature and the behavior of quasiparticles in OIHPs.

Download or read book Atomic Structure Electronic States and Relaxation Dynamics in Photovoltaic Materials and Interfaces from Photoemission related Spectroscopies written by Min-I. Lee and published by . This book was released on 2018 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The efficiency of the photovoltaic process depends on the electronic band structure of the active material and the charge carrier dynamics. In this thesis, we have studied how these issues are related to the atomic structure in materials for two different technologies of solar cells, namely silicon heterostructure solar cells, and hybrid organic-inorganic perovskite solar cells. In silicon heterostructure solar cells, we have analyzed the impact of defects on the electronic properties of amorphous silicon heterostructures (a-Si:H/a-SIC:H/c-Si) by core level and valence band spectroscopies. In particular, we have quantified the number of dangling bonds inside a-Si:H layer upon irradiation, we have identified the electronic states associated to them, and we have understood the transitions previously observed by photoluminescence. In perovskite solar cells, we have correlated the atomic structure, the electronic structure and the electronic dynamics for two- and three-dimensional hybrid organic-inorganic perovskites. We have used with this goal a whole panel of complementary techniques: X-ray diffraction, angle-resolved photoemission spectroscopy, inverse photoemission spectroscopy, and time-resolved two-photon photoemission. In the two-dimensional perovskite (C6H5C2H4NH3)2PbI4, the valence and conduction bands have been determined experimentally and compared to spectral function simulations. In the three-dimensional perovskite CH3NH3PbI3, we have again determined the band structure and simulated it. Very broad spectral features have been experimentally observed, which relax the optical transition conditions impacting in the solarcell efficiencies. In both experiments and calculations, we observe that the spectral weight follows a cubic periodicity while the system is structurally in the tetragonal phase. This apparent contradiction is explained by the band broadness, which hides the band folding of the tetragonal distortion. As for the relaxation dynamics, we have observed that the photoexcited carriers thermalize in a subpicosecond time scale through the coupling to organic cation vibrations. At longer timescales (10~100 picoseconds), the electron diffusion controls the dynamics. This dynamics is affected by the annealing-induced defects, which localize the photoexcited electrons for more than 300 picoseconds.

Download or read book Enhanced Charge Carrier Dynamics and Defects Passivation in Hybrid Perovskite Solar Cell Using a Novel Organic Halide Salt written by MD Ashiqur Rahman Laskar and published by . This book was released on 2020 with total page 134 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Emerging Photovoltaic Technologies written by Carlito S. Ponseca and published by CRC Press. This book was released on 2019-12-19 with total page 242 pages. Available in PDF, EPUB and Kindle. Book excerpt: The need to address the energy problem and formulate a lasting solution to tame climate change has never been so urgent. The rise of various renewable energy sources, such as solar cell technologies, has given humanity a glimpse of hope that can delay the catastrophic effects of these problems after decades of neglect. This review volume provides in-depth discussion of the fundamental photophysical processes as well as the state-of-the-art device engineering of various emerging photovoltaic technologies, including organic (fullerene, non-fullerene, and ternary), dye-sensitized (ruthenium, iron, and quantum dot), and hybrid metal-halide perovskite solar cells. The book is essential reading for graduate and postgraduate students involved in the photophysics and materials science of solar cell technologies.

Download or read book Hybrid Perovskite Solar Cells written by Hiroyuki Fujiwara and published by John Wiley & Sons. This book was released on 2022-01-10 with total page 612 pages. Available in PDF, EPUB and Kindle. Book excerpt: Unparalleled coverage of the most vibrant research field in photovoltaics! Hybrid perovskites, revolutionary game-changing semiconductor materials, have every favorable optoelectronic characteristic necessary for realizing high efficiency solar cells. The remarkable features of hybrid perovskite photovoltaics, such as superior material properties, easy material fabrication by solution-based processing, large-area device fabrication by an inkjet technology, and simple solar cell structures, have brought enormous attentions, leading to a rapid development of the solar cell technology at a pace never before seen in solar cell history. Hybrid Perovskite Solar Cells: Characteristics and Operation covers extensive topics of hybrid perovskite solar cells, providing easy-to-read descriptions for the fundamental characteristics of unique hybrid perovskite materials (Part I) as well as the principles and applications of hybrid perovskite solar cells (Part II). Both basic and advanced concepts of hybrid perovskite devices are treated thoroughly in this book; in particular, explanatory descriptions for general physical and chemical aspects of hybrid perovskite photovoltaics are included to provide fundamental understanding. This comprehensive book is highly suitable for graduate school students and researchers who are not familiar with hybrid perovskite materials and devices, allowing the accumulation of the accurate knowledge from the basic to the advanced levels.

Download or read book The Uncommon Nature of Point Defects in Organic inorganic Perovskite Solar Cells written by Olivia Dolores Hentz and published by . This book was released on 2018 with total page 148 pages. Available in PDF, EPUB and Kindle. Book excerpt: Organic-inorganic perovskite solar cells (PSCs) have shown enormous success in the past decade, increasing in power conversion efficiency from ~4% in 2009 to >22%. One of the critical properties that contributed to this success is “defect tolerance”: in organic-inorganic perovskites, the majority of point defects with low formation energy are shallow, with energies within or near the conduction or valence band. Defects with deep states, which act as electronic traps, are expected to be much less common due to their high formation energies. In this thesis, we demonstrate that, despite the preference for shallow defects, point defects play an integral role in materials properties and PSC device performance. We first study the role of point defects on nanoscale luminescence properties of inorganic-organic perovskites by using cathodoluminescence in scanning transmission electron microscopy (STEM). By correlating local luminescence properties with compositional variations using STEM, we demonstrate that iodide segregation induced by the electron beam is correlated with a spatially-localized high-energy emission. Similar high-energy emission has been observed in photoluminescence (PL) measurements for films made in the presence of excess methyl ammonium iodide, demonstrating that the observed defect segregation is relevant to practical device design. Next, we study the effects of directional point defect segregation under an applied electric field on current extraction from PSCs. Specifically, we use electron beam-induced current measurements in a scanning electron microscope to measure the inhomogeneity in current extraction before and after forward biasing the device. These measurements point to preferential defect migration at extended defects and allow us identify low frequency capacitive elements related to compensation of charged defect segregation under applied biasing. Finally, we directly track the migration of deep defects in PSCs through photoluminescence mapping of laterally biased perovskite films. Removal of defect states by mild voltage biasing results in over an order of magnitude increase in luminescence. Using Monte Carlo simulations of defect drift and diffusion to model these time dependent luminescence maps, we extract the mobility of these point defects and provide evidence of demonstrates the ways in which deep and shallow defects play a critical role in PSCs and suggests that, despite their “defect tolerance,” the ultimate stability and performance of PSCs will be dependent on either minimizing the presence of point defects in these materials or inhibiting defect migration.

Download or read book Perovskite Photovoltaics and Optoelectronics written by Tsutomu Miyasaka and published by John Wiley & Sons. This book was released on 2022-03-21 with total page 484 pages. Available in PDF, EPUB and Kindle. Book excerpt: Perovskite Photovoltaics and Optoelectronics Discover a one-of-a-kind treatment of perovskite photovoltaics In less than a decade, the photovoltaics of organic-inorganic halide perovskite materials has surpassed the efficiency of semiconductor compounds like CdTe and CIGS in solar cells. In Perovskite Photovoltaics and Optoelectronics: From Fundamentals to Advanced Applications, distinguished engineer Dr. Tsutomu Miyasaka delivers a comprehensive exploration of foundational and advanced topics regarding halide perovskites. It summarizes the latest information and discussion in the field, from fundamental theory and materials to critical device applications. With contributions by top scientists working in the perovskite community, the accomplished editor has compiled a resource of central importance for researchers working on perovskite related materials and devices. This edited volume includes coverage of new materials and their commercial and market potential in areas like perovskite solar cells, perovskite light-emitting diodes (LEDs), and perovskite-based photodetectors. It also includes: A thorough introduction to halide perovskite materials, their synthesis, and dimension control Comprehensive explorations of the photovoltaics of halide perovskites and their historical background Practical discussions of solid-state photophysics and carrier transfer mechanisms in halide perovskite semiconductors In-depth examinations of multi-cation anion-based high efficiency perovskite solar cells Perfect for materials scientists, crystallization physicists, surface chemists, and solid-state physicists, Perovskite Photovoltaics and Optoelectronics: From Fundamentals to Advanced Applications is also an indispensable resource for solid state chemists and device/electronics engineers.

Download or read book Investigation of Charge Carrier Dynamics in Organo halide Perovskite and Colloidal Quantum Dot Semiconductors written by Robert Stewart and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Crystallite surfaces often dominate the optical and electronic properties of nanocrystalline semiconductors because the fraction of atoms at the surface experience different crystal field environments than bulk atoms, and as a consequence, surfaces influence the energetic landscape of the entire crystallite. Contributing electronic states that are either isoenergetic or below the semiconductor band edges, surface states mediate charge conduction and recombination - two critical processes in optoelectronic device performance. Utilizing a combination of inorganic synthesis, surface characterization, and time-resolved optical spectroscopy, the research presented herein begins to identify the link between charge carrier dynamics and the underlying surface chemistry in two emerging, yet promising, nanocrystal semiconductor systems: organo-halide perovskites and colloidal quantum dots (CQD).Notably, my research provided one of the first reports that charge recombination centers in lead halide perovskite films are localized almost exclusively on the surface of crystallites. Passivation of these nanocrystal surfaces with small molecules that contain strongly coordinating functional groups caused charge-carrier lifetimes in perovskite thin-films to approach the bulk radiative limit reported for single crystal analogues. Likewise, my research contributed to an understanding that surfaces in lead sulfide (PbS) CQDs produce electronic energy levels that are sufficiently delocalized to provide charge conduction pathways in CQD thin-film arrays. Given the strong coupling to the QD surface, charge carrier diffusion lengths were shown to be highly sensitive to the character of surface-bound ligands. My PhD research highlights the importance of understanding the interplay between surface chemistry and nanocrystal semiconductor photophysics as wellivas the importance of selecting surface treatment strategies capable of passivating diversesurfaces to eliminate energetic inhomogeneity while simultaneously allowing strongelectronic coupling across interfaces.

Download or read book Defects and Surface Induced Effects in Advanced Perovskites written by Gunnar Borstel and published by Springer Science & Business Media. This book was released on 2000-03-31 with total page 518 pages. Available in PDF, EPUB and Kindle. Book excerpt: Complex oxide materials, especially the ABO3-type perovskite materials, have been attracting growing scientific interest due to their unique electro-optical properties, leading to photorefractive effects that form the basis for such devices as holographic storage, optical data processing and phase conjugation. The optical and mechanical properties of non-metals are strongly affected by the defects and impurities that are unavoidable in any real material. Nanoscopically sized surface effects play an important role, especially in multi-layered ABO3 structures, which are good candidates for high capacity memory cells. The 51 papers presented here report the latest developments and new results and will greatly stimulate progress in high-tech technologies using perovskite materials.

Download or read book Perovskite Photovoltaics written by Aparna Thankappan and published by Academic Press. This book was released on 2018-06-29 with total page 521 pages. Available in PDF, EPUB and Kindle. Book excerpt: Perovskite Photovoltaics: Basic to Advanced Concepts and Implementation examines the emergence of perovskite photovoltaics, associated challenges and opportunities, and how to achieve broader development. Consolidating developments in perovskite photovoltaics, including recent progress solar cells, this text also highlights advances and the research necessary for sustaining energy. Addressing different photovoltaics fields with tailored content for what makes perovskite solar cells suitable, and including commercialization examples of large-scale perovskite solar technology. The book also contains a detailed analysis of the implementation and economic viability of perovskite solar cells, highlighting what photovoltaic devices need to be generated by low cost, non-toxic, earth abundant materials using environmentally scalable processes. This book is a valuable resource engineers, scientists and researchers, and all those who wish to broaden their knowledge on flexible perovskite solar cells. - Includes contributions by leading solar cell academics, industrialists, researchers and institutions across the globe - Addresses different photovoltaics fields with tailored content for what makes perovskite solar cells different - Provides commercialization examples of large-scale perovskite solar technology, giving users detailed analysis on the implementation, technical challenges and economic viability of perovskite solar cells

Download or read book Defect Passivation in Hybrid Perovskite Solar Cells by Zwitterions written by Xiaopeng Zheng and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The ionic defects on the surfaces and at the grain boundaries of organic-inorganic halide perovskite films are detrimental to the efficiency and stability of perovskite solar cells. In chapter 3, we showed that the zwitterions can effectively passivate ionic defects in several different types of hybrid perovskites with negatively and positively charged components. The efficient defect passivation reduces the charge-trap density and extends the carrier recombination lifetime- supported by calculating the density function. The defect passivation reduces the open-circuit-voltage deficit of the p-i-n structured device to 0.39 V and boosts the efficiency to a certified value of 20.59±0.45%. Moreover, the defect healing also significantly enhances the stability of films in ambient conditions. Our findings provide an avenue for defect passivation to further improve the efficiency and stability of solar cells. The uniform and high-electronic-quality of perovskite thin films are essential for high-performance perovskite devices. Here, it was shown that the 3-[Dodecyl(dimethyl)ammonio]-1-propanesulfonate inner salt (DPSI), which is a zwitterionic lead (II)-coordination long chain molecule, plays dual roles in tuning the crystallization behavior and passivating defects of perovskites. The synergistic effect of crystallization control and defect passivation remarkably suppresses the pin-hole formation, reduces the charge trap density, and elongates the carrier recombination lifetime, boosting the planar perovskite device efficiency to 21.1%. Our findings provide an avenue for simultaneous crystallization control and defect passivation to further improve the performance of perovskite devices.