Electrical and optical characterization of CdxZn1-xS and PbS thin films for photovoltaic applications PDF Download
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Author: Cliff Orori Mosiori
Publisher: GRIN Verlag
ISBN: 3656718407
Category : Science
Languages : en
Pages : 118
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Book Description
Master's Thesis from the year 2011 in the subject Physics - Applied physics, grade: A, Kenyatta University, course: Master of Science ( Physics), language: English, abstract: In this research an n-type CdxZn1-xS and p-type PbS thin films were optimised for solar cell applications employing chemical bath deposition technique. The thin films were prepared using thiourea and nitrates of cadmium, zinc and lead. Deposition of optimised CdxZn1-xS was done by CBD at 820 C and in alkaline conditions while that of PbS was done at room temperature and both films at normal atmospheric pressure utilizing aqueous conditions. This study concentrated on optimising optical and electrical characterization of the films. Optical constant suitable for photovoltaic applications were sort for and for this purpose a UV VIS IR spectrophotometer 3700 DUV was utilised while the electrical properties were investigated using a four point probe connected to a Keithley 2400 source meter interfaced with computer. The optical band gap of the as deposited CdxZn1-xS films varied from 2.47eV (x =0.6) to 2.72 eV (x =1.0), and transmittance above 79% in the VIS - NIR region for the concentration range of x = 0.6 to 1.0, that is, the band gap increased with increasing Zn concentration of the alloy and Cd06Zn0.4S sample showed the widest band gap. It was obtained that the presence of zinc increased optical band gap. The average extinction coefficients for the as deposited CdxZn1-xS samples were very low revealing that they absorb very little radiation hence a good window layer material. As measured by the four point probe connected to a Keithley 2400 source meter, electrical resistivity increased with increase in Zn in the bath in CdxZn1-xS and a resistivity range of 9.5×101 – 1.22× 102 Ω-cm was obtained. These properties are appropriate for window layers used for photovoltaic cell applications. PbS thin films had a band gap of 0.89 eV and a transmittance of below 55% appropriate for absorber layers of photovoltaic cells and a resistivity range of 6.78 × 103 to 1.26 × 104 Ω-cm. The fabricated photovoltaic cell had a short circuit current, Isc = 0.031 A, open voltage, Voc = 0.37V, efficiency, η = 0.9% and a fill factor, FF = 0.66 implying that the two materials are appropriate for photovoltaic applications especially in the VIS and IR light spectrum.
Author: Cliff Orori Mosiori
Publisher: GRIN Verlag
ISBN: 3656718407
Category : Science
Languages : en
Pages : 118
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Book Description
Master's Thesis from the year 2011 in the subject Physics - Applied physics, grade: A, Kenyatta University, course: Master of Science ( Physics), language: English, abstract: In this research an n-type CdxZn1-xS and p-type PbS thin films were optimised for solar cell applications employing chemical bath deposition technique. The thin films were prepared using thiourea and nitrates of cadmium, zinc and lead. Deposition of optimised CdxZn1-xS was done by CBD at 820 C and in alkaline conditions while that of PbS was done at room temperature and both films at normal atmospheric pressure utilizing aqueous conditions. This study concentrated on optimising optical and electrical characterization of the films. Optical constant suitable for photovoltaic applications were sort for and for this purpose a UV VIS IR spectrophotometer 3700 DUV was utilised while the electrical properties were investigated using a four point probe connected to a Keithley 2400 source meter interfaced with computer. The optical band gap of the as deposited CdxZn1-xS films varied from 2.47eV (x =0.6) to 2.72 eV (x =1.0), and transmittance above 79% in the VIS - NIR region for the concentration range of x = 0.6 to 1.0, that is, the band gap increased with increasing Zn concentration of the alloy and Cd06Zn0.4S sample showed the widest band gap. It was obtained that the presence of zinc increased optical band gap. The average extinction coefficients for the as deposited CdxZn1-xS samples were very low revealing that they absorb very little radiation hence a good window layer material. As measured by the four point probe connected to a Keithley 2400 source meter, electrical resistivity increased with increase in Zn in the bath in CdxZn1-xS and a resistivity range of 9.5×101 – 1.22× 102 Ω-cm was obtained. These properties are appropriate for window layers used for photovoltaic cell applications. PbS thin films had a band gap of 0.89 eV and a transmittance of below 55% appropriate for absorber layers of photovoltaic cells and a resistivity range of 6.78 × 103 to 1.26 × 104 Ω-cm. The fabricated photovoltaic cell had a short circuit current, Isc = 0.031 A, open voltage, Voc = 0.37V, efficiency, η = 0.9% and a fill factor, FF = 0.66 implying that the two materials are appropriate for photovoltaic applications especially in the VIS and IR light spectrum.
Author: Cliff Orori Mosiori
Publisher: LAP Lambert Academic Publishing
ISBN: 9783659414039
Category :
Languages : en
Pages : 120
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Book Description
A study of CdZnS and PbS nano-crystalline thin films deposited by chemical bath deposition (CBD) method has been made using Four point probe for electrical sheet resistivity, UV-Vis spectroscopy and solar simulator for optical and Photovoltaic cell properties respectively. Sheet resistivity for CdZnS thin films was found to decrease as the concentration of Zn increased while PbS thin films had their sheet resistivity increase with increase in bath concentrations. Optical band gap for CdZnS had a tunability depending on the various Zn2+ concentrations used successfully as demonstrated by UV-VIS-NIR spectroscopy. Transmittance in CdxZn1-xS was found to be above 80%, optical band gap of 2.47 - 2.72 eV, refractive index of 2.58 - 2.39, and sheet resistivity of 1.09 - 1.36 x 102 -cm for x = 1.0 - 0.6. The thin films were suitable for use as window films for optical devices. PbS films were good absorbers with a band gap of 0.88 eV and transmittance below 55%, Electrical resistivity varying from 6.78 x 103 to 1.26 x 104 -cm, conductivity of 1.09 x 10-4 to 7.9 x 10-5 S-cm-1. The PbS films were suitable as absorber films for photovoltaic cell applications.
Author: Cliff Orori Mosiori
Publisher: diplom.de
ISBN: 3954898462
Category : Technology & Engineering
Languages : en
Pages : 220
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Book Description
Thin films can be used to fabricate optoelectronic devices. Technology is currently focusing on ternary thin film composition because of their structure, inter-band transitions and other optical properties that can be maximized. This book discusses in detail the optical characteristics of ternary thin films and further investigates the behavior of Iron Zinc Sulphide, Lead Silver Sulphide, Copper Silver Sulphide, Copper Zinc Sulphide and Cadmium Zinc Sulphide. Thin films are of fundamental importance in modern technology.
Author: Cliff Orori Mosiori
Publisher: Anchor Academic Publishing
ISBN: 3954894327
Category : Science
Languages : en
Pages : 393
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Book Description
Solid state physics is a fascinating sub-genre of condensed matter physics - though some graduate students consider it a very boring and tedious subject area in Physics and others even call it a “squalid state”. Topics covered in this book are built on standard solid state physics references available in most online libraries or in other books on solid state physics. The complexity of high speed semiconductor physics and related devices arose from condensed solid state matter. The content covered in this book gives a deep coverage on some topics or sections that may be covered only superficially in other literature. Therefore, these topics are likely to differ a great deal from what is deemed important elsewhere in other books or available literature. There are many extremely good books on solid-state physics and condensed matter physics but very few of these books are restricted to high speed semiconductor physic though. Chapter one covers the general semiconductor qualities that make high speed semiconductor devices effect and includes the theory of crystals, diffusion and ist mechanisms, while chapter two covers solid state materials, material processing for high speed semiconductor devices and an introduction to quantum theory for materials in relation to density of states of the radiation for a black body and ist radiation properties. Chapter three discuss high speed semiconductor energy band theory, energy bands in general solid semiconductor materials, the Debye model, the Einstein model the Debye model and semiconductor transport carriers in 3D semiconductors while chapter four discuss effect of external force on current flow based on the concept of holes valence band, and lattice scattering in high speed devices. Chapter five briefly describes solid state thermoelectric fundamentals, thermoelectric material and thermoelectric theory of solids in lattice and phonons while chapter six scattering in high field effect in semiconductors in inter-valley electron scattering and the associated Fermi Dirac statistics and Maxwell-Boltzmann approximation on their carrier concentration variation with energy in extrinsic doping chapter seven covers p-n junction diodes, varactor diode, pin diode Schottky diode and their transient response of diode in multi-valley semiconductors. Chapter eight discusses high speed metal semiconductor field effect transistors.
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Category :
Languages : ko
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Author: Anna Osherov
Publisher:
ISBN:
Category : Electrophoretic deposition
Languages : en
Pages : 128
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Author: Erin Elizabeth Jedlicka
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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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.
Author: Amanda P. Christmas
Publisher:
ISBN:
Category : Indium
Languages : en
Pages :
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Author: Yu N. Korkishko
Publisher: Cambridge Int Science Publishing
ISBN: 189832641X
Category : Technology & Engineering
Languages : en
Pages : 531
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Book Description
The book addresses many problems of ion exchange processes in LiNbO3, LiTaO3 and KTiOPO4 ferroelectrics and II-VI semiconductor single crystals for integrated optics applications. The authors start with the fundamentals of ion exchange processes in solids (Chapter 1). Chapter 1 can be considered also as an enlarged introduction to the book. Starting with Chapter 2, the general properties of LiNbO3 and LiTaO3 crystals, the methods used to study optical waveguides in these crystals as well as advanced preparation methods of optical waveguides are reviewed. Chapters 3, 4 and 5 are devoted to recent progress in the ion exchange processes in LiNbO3, LiTaO3 and KTiOPO4 crystals, respectively, and Chapter 6 summarizes the main applications of ion-exchanged waveguides in modern integrated optics. Finally, Chapter 7 deals with recently established ion exchange processes in II-VI semiconductors.
Author: Hee Joon Jung
Publisher:
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Category :
Languages : en
Pages :
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The world's growing energy needs will involve not one but a harmonious collection of extremely efficient energy technologies that will work in concert to produce, store, and use the large amounts of energy that humans will soon demand. To provide a scientific establishment for break-out high-efficiency, cost-effective energy technologies, research activities have been focused on manipulation of materials at the nanometer scale to increase efficiency of energy conversion devices and exploitation of fundamental advances in charge transport, light absorption, and reaction thermodynamics and kinetics to improve performance and efficiency in energy conversion devices like solar cell, fuel cell, and photoelectrochemical (PEC) cell. To achieve these goals, we need to understand how nano-structuring modifies and governs the properties of materials, and how to control dimensionality and confinement to learn insights on model energy conversion materials, structures and devices. Transmission Electron Microscopy (TEM) with additional advanced functions enables us to approach profound understanding of the fundamental relationship between chemical / electronic / optical properties of materials and origin (crystal structure, composition, size, shape) of them through the characterization at atomic or nano/micro scale. This dissertation will mainly deal with the TEM characterization on the energy-related materials for the solar cell and fuel cell (especially, solid oxide fuel cell) using a variety of different TEM techniques. The most of sample was prepared by conventional TEM preparation method or site-specific lift-out technique using a focused ion beam (FIB). Subsequent TEM studies on these energy-related materials lead to have deep understanding of the relationship between the atomic scale structures with the other chemical/optical/electronic property. In the chapter 1, the brief concept and background of the solar cell and fuel cell will be included. In the chapter 2, the details of TEM/STEM background for imaging and diffraction with a variety of additional TEM spectroscopic techniques like X-ray energy dispersive (EDS) and electron energy loss spectroscopy (EELS) are included because this dissertation is mainly focused on TEM characterization. And the background of FIB/SEM and sample preparation using FIB is followed. In the chapter 3, the TEM characterization on the diverse kinds of materials of the 2nd and 3rd generation solar cells mainly made by atomic layer deposition (ALD) is dealt with using different types of spectroscopic techniques. ZnS, CdS, ZnxCd1-xS, PbS deposited by ALD for the 2nd and 3rd generation solar cell and the advanced bottom electrode structure are included. Each sub-chapter in the chapter 3 is based on the published papers as follows: Chapter 3-2: "Atomic layer deposition of ZnS via in situ production of H2S", J.R. Bakke, J.S. King, H.J. Jung, R. Sinclair, S.F. Bent, Thin Solid Films. 518. pp. 5400-5408 (2010). Chapter 3-3: "Atomic Layer Deposition of CdS Films", Jonathan R. Bakke, Hee Joon Jung, Jukka T. Tanskanen, Robert Sinclair, and Stacey F. Bent, Chem. Mater. 22, 4669-4678 (2010). Chapter 3-4: "Atomic Layer Deposition of CdxZn1-xS Films", Jonathan. R. Bakke, Jukka T. Tanskanen, Hee Joon Jung, Robert Sinclair, Stacey F. Bent, J. Mater. Chem., 21, 743-751 (2011). Chapter 3-5: "Scanning Tunneling Spectroscopy of Lead Sulfide Quantum Wells Fabricated by Atomic Layer Deposition for Band Gap Engineering", Wonyoung Lee, Neil P. Dasgupta, Hee Joon Jung, Jung-Rok Lee, Robert Sinclair and Fritz B. Prinz, Nanotechnology, 21, 485402, 4pp. (2010). Chapter 3-6: "Atomic Layer Deposition of Lead Sulfide Quantum Dots on Nanowire Surfaces", Hee Joon Jung, Neil Dasgupta, Orlando Trejo, Matthew T. McDowell, Aaron Hryciw, Mark Brongersma, Robert Sinclair and Fritz B. Prinz, Nano Lett., 11 (3), pp 934-940 (2011). Chapter 3-7: "Evidence For Shape-Induced Bandgap Variations Within a Single Quantum Dot", Hee Joon Jung, Neil P. Dasgupta, Philip B. Van Stockum, Ai Leen Koh, Robert Sinclair, Nature Nanotehchnol., (2012) under review. Chapter 3-8: "Nickel Silicide Nanowire Arrays for Anti-Reflective Electrodes in Photovoltaics", Neil P. Dasgupta, Shicheng Xu, Hee Joon Jung, Andrei Iancu, Rainer Fasching, Robert Sinclair, Fritz B. Prinz, Adv. Funct. Mater., Vol. 22, Issue 17, 3650-3657 (2012). In chapter 4, the TEM characterization on the materials of the solid oxide fuel cells which Yttrium-doped Barium Zirconate (BYZ) by the atomic layer deposition (ALD) and Gadolinia (Ge2O3)-doped Ceria (CeO2) by the pulsed laser deposition (PLD) is dealt with. Each sub-chapter in the chapter 4 is based on the published papers as follows: Chapter 4-2: "Effect of crystallinity on ionic conductivity of Y-doped Barium Zirconate", Y.B. Kim, T.M. Gur, H.J. Jung, S. Kang, R. Sinclair, F.B. Prinz, Solid State Ionics, Vol. 198, Issue 1, 19, 39-46 (2011). Chapter 4-3: "Oxygen Surface Exchange at Grain Boundaries of Oxide Ion Conductors", Wonyoung Lee, Hee Joon Jung, Min Hwan Lee, Young-Beom Kim, Joong Sun Park, Robert Sinclair, and Fritz B. Prinz, Adv. Funct. Mater., Vol. 22, Issue 5, 965--971 (2012).
