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Wide Bandgap Organo‐Lead Trihalide Perovskites For Solar Cells, Miao Hu 2016 University of Nebraska-Lincoln

Wide Bandgap Organo‐Lead Trihalide Perovskites For Solar Cells, Miao Hu

Mechanical (and Materials) Engineering -- Dissertations, Theses, and Student Research

Methylammonium lead trihalide perovskite (MAPbX3, where MA is methylammonium, and X is a halide)-based solar cells have been extensively investigated recently, with a demonstrated and certified solar power conversion efficiency (PCE) exceeding 20%. To further boost the PCE beyond the Schockley–Queisser limit, tandem structured solar cells have been investigated based on integrating MAPbX3 and the lower bandgap solar cells. Although the best reported efficiency for this type of tandem cells is not close to the theoretically achievable value, mixed-halide perovskite MAPbBrxI3–x is still one of the most promising candidates as the wide-bandgap light absorber for the tandem ...


Zno Thin Films Generated By Ex-Situ Thermal Oxidation Of Metallic Zn For Photovoltaic Applications, Kovas Zygas 2016 Macalester College

Zno Thin Films Generated By Ex-Situ Thermal Oxidation Of Metallic Zn For Photovoltaic Applications, Kovas Zygas

Macalester Journal of Physics and Astronomy

ZnO thin films that function as either transparent conducting oxides in solid-state photovoltaic cells or as nanocrystalline dye-absorbers in dye-sensitized solar cells have the potential to reduce the cost of producing electricity from solar energy. Although there exist many methods to produce ZnO thin films, the most economical and practical method may be oxidation of metallic Zn thin films. This research examined the utility of ex-situ thermal oxidation of DC magnetron sputtered Zn thin films in generating useful ZnO thin films for these photovoltaic applications. We annealed Zn thin films in air at 570° C in order to produce ZnO ...


Symbiotic Plasmonic Nanomaterials: Synthesis And Properties, Abhinav Malasi 2016 University of Tennessee - Knoxville

Symbiotic Plasmonic Nanomaterials: Synthesis And Properties, Abhinav Malasi

Doctoral Dissertations

Metal particles of the dimensions of the order of 1 to 100's of nanometers show unique properties that are not clearly evident in their bulk state. These nanoparticles are highly reactive and sensitive to the changes in the vicinity of the particle surface and hence find applications in the field of sensing of chemical and biological agents, catalysis, energy harvesting, data storage and many more. By synthesizing bimetallic nanoparticles, a single nanoparticle can show multifunctional characteristics. The focus of this thesis is to detail the synthesis and understand the properties of bimetallic nanomaterial systems that show interesting optical, chemical ...


Synthesis Of Acceptors For Use In Donor-Acceptor Copolymers And Characterization Of These Polymers, William D. Walker 2016 The University of Southern Mississippi

Synthesis Of Acceptors For Use In Donor-Acceptor Copolymers And Characterization Of These Polymers, William D. Walker

Honors Theses

In this thesis, a selenium-derivatized acceptor was synthesized to examine the heavy atom effects of selenium on the position of the frontier molecular orbitals (HOMO/LUMO band gap) as opposed to sulfur in a donor-acceptor copolymer for use in light harvesting and detection applications. Over the course of this research, standard operating protocols for ultraviolet-visible (UV-Vis-NIR) and Fourier transform infrared (FT-IR) spectroscopies, as well as cyclic voltammetry (CV) characterization techniques were established. Once synthesized, the polymers were characterized through use of the established characterization protocols. The selenium-derivatized polymer exhibited a bathochromic shift compared to the sulfur analogue, with a solid-state ...


Manipulation Of Surface Plasmon Resonance In Metal And Alloy Thin Films Using Dielectric Media, Benjamin DuBray Hall 2016 Rose-Hulman Institute of Technology

Manipulation Of Surface Plasmon Resonance In Metal And Alloy Thin Films Using Dielectric Media, Benjamin Dubray Hall

Graduate Theses - Physics and Optical Engineering

Surface plasmon polaritons are coherent electron oscillations that propagate along an interface between a Drude metal and a dielectric medium. The excitation of polaritons is highly dependent on the dielectric properties of the metal, the thickness of the metal, and the optical properties of the dielectric material. First, plasmonic activity is assessed for several thicknesses of silver and nickel chromium under He-Ne incidence. Relationships between film thickness and metal dielectric function are explored in both cases. To manipulate the plasmonic activity at the silver surfaces, two methods are explored. Silver oxide was grown on the surface of the silver films ...


Synthesis, Characterization, And Electronic Properties Of Novel 2d Materials : Transition Metal Dichalcogenides And Phosphorene., George Anderson 2016 university of louisville

Synthesis, Characterization, And Electronic Properties Of Novel 2d Materials : Transition Metal Dichalcogenides And Phosphorene., George Anderson

Electronic Theses and Dissertations

Scaling electronic devices has become paramount. The current work builds upon scaling efforts by developing novel synthesis methods and next generation sensing devices based on 2D materials. A new combination method utilizing thermal evaporation and chemical vapor deposition was developed and analyzed to show the possibilities of Transition Metal Dichalcogenide monolayers and heterostructures. The materials produced from the above process showed high degrees of compositional control in both spatial dimensions and chemical structure. Characterization shows controlled fabrication of heterostructures, which may pave the way for future band gap engineering possibilities. In addition, Phosphorene based field effect transistors, photodetectors, and gas ...


Direct Band Gap Gallium Antimonide Phosphide (Gasbxp1-X) For Solar Fuels., Harry Benjamin Russell 2016 University of Louisville

Direct Band Gap Gallium Antimonide Phosphide (Gasbxp1-X) For Solar Fuels., Harry Benjamin Russell

Electronic Theses and Dissertations

Photoelectrochemical water splitting has been identified as a promising route for achieving sustainable energy future. However, semiconductor materials with the appropriate optical, electrical and electrochemical properties have yet to be discovered. In search of an appropriate semiconductor to fill this gap, GaSbP, a semiconductor never tested for PEC performance is proposed here and investigated. Density functional theory (DFT+U) techniques were utilized to predict band gap and band edge energetics for GaSbP alloys with low amount of antimony. The overall objective of this dissertation is to understand the suitability of GaSbxP1-x alloys for photoelectrochemical water splitting application ...


Thermal Characteristics Of Lithium Indium Diselenide And Lithium Indium Gallium Diselenide Neutron Detection Crystals, Dustin Carroll Giltnane 2016 University of Tennessee - Knoxville

Thermal Characteristics Of Lithium Indium Diselenide And Lithium Indium Gallium Diselenide Neutron Detection Crystals, Dustin Carroll Giltnane

Masters Theses

Tracking special nuclear materials (SNM) has never been more important than in the 21st century where information is transferred rapidly around the globe. Tracking SNM is important to nuclear power, weapons, medicine, and science. Neutron and gamma ray detection are the primary methods of detecting SNM. Increased movement and availability of SNM have increased the demand for radiation detection systems beyond the capacity of traditional neutron detection technologies (3He) [Helium three]. Many alternative neutron detection materials are being considered, including 6LiInSe2 [Lithium Indium Diselenide grown with lithium enriched in lithium six] and its derivative 6LiIn ...


Magnetic, Optical And Electrical Properties Of Electron-Hole Pairs In Polymer And Organo-Metal Halide Perovskite Photovoltaic Cells, Yu-Che Hsiao 2016 University of Tennessee - Knoxville

Magnetic, Optical And Electrical Properties Of Electron-Hole Pairs In Polymer And Organo-Metal Halide Perovskite Photovoltaic Cells, Yu-Che Hsiao

Doctoral Dissertations

Organic polymer and organo-metal halide perovskite (OMHP) materials have attracted extensive attention during the past decade due to their various applications, like solar cells, light emitting diode, even lasing action (OMHP). Especially, the organo-metal halide perovskite solar cell shows a remarkable power conversion efficiency of about 20%, which is comparable to the amorphous silicon solar cell. Therefore, OMHP solar cell had been considered as a promising substitution for the next generation of renewable energy source. The OMHP materials contain both advantages of organic and inorganic semiconductors, like solution processable thin film fabrication, long-range ambipolar transport characteristics, high dielectric constants, low ...


Growth Of Ws2 Thin Photovoltaic Films, Matthew J. Hilfiker, Aaron Ediger, Natale lanno 2016 University of Nebraska - Lincoln

Growth Of Ws2 Thin Photovoltaic Films, Matthew J. Hilfiker, Aaron Ediger, Natale Lanno

UCARE Research Products

Through research for a material that is low cost, earth abundant, and highly efficient, Tungsten Sulfide (WS2) has been identified as a promising solution. From literature, it has been shown that WS2 possesses a band gap of 1.9 eV, which is ideal for a top layer heterostructure cell. While this is a favorable value, other properties needed to understand its value as a photovoltaic material are unknown. Through research, WS2 films will be grown through a sputtering deposition process and electrical characterization measurements will be performed to study these missing properties.


Spin-Gapless Semiconductivity And Half Metallicity In Heusler Alloys, Bradley A. Staten 2016 University of Northern Iowa

Spin-Gapless Semiconductivity And Half Metallicity In Heusler Alloys, Bradley A. Staten

Research in the Capitol

In recent years, ever increasing interest in spin-based electronics (spintronics) has resulted in the search for a new class of materials that can provide a high degree of transport spin polarization. An ideal candidate would act like insulator for one spin channel and a conductor or semiconductor for the opposite spin channel (e.g. half metals (HM), spin gapless semiconductors (SGS)). In this work, we present results of our computational and theoretical study (Staten, et al., J. Appl. Phys. 117, 17D115 (2015)) of Heusler compounds with potential commercial applications in the field of spintronics. We show that naturally these materials ...


Zncdmgse As A Materials Platform For Advanced Photonic Devices: Broadband Quantum Cascade Detectors And Green Semiconductor Disk Lasers, Joel De Jesus 2016 Graduate Center, City University of New York

Zncdmgse As A Materials Platform For Advanced Photonic Devices: Broadband Quantum Cascade Detectors And Green Semiconductor Disk Lasers, Joel De Jesus

All Graduate Works by Year: Dissertations, Theses, and Capstone Projects

The ZnCdMgSe family of II-VI materials has unique and promising characteristics that may be useful in practical applications. For example they can be grown lattice matched to InP substrates with lattice matched bandgaps that span from 2.1 to 3.5 eV, they can be successfully doped n-type, have a large conduction band offset (CBO) with no intervalley scattering present when strained, they have lower average phonon energies, and the InP lattice constant lies in the middle of the ZnSe and CdSe binaries compounds giving room to experiment with tensile and compressive stress. However they have not been studied in ...


Beyond Conventional C-Plane Gan-Based Light Emitting Diodes: A Systematic Exploration Of Leds On Semi-Polar Orientations, Morteza Monavarian 2016 Virginia Commonwealth University

Beyond Conventional C-Plane Gan-Based Light Emitting Diodes: A Systematic Exploration Of Leds On Semi-Polar Orientations, Morteza Monavarian

Theses and Dissertations

Despite enormous efforts and investments, the efficiency of InGaN-based green and yellow-green light emitters remains relatively low, and that limits progress in developing full color display, laser diodes, and bright light sources for general lighting. The low efficiency of light emitting devices in the green-to-yellow spectral range, also known as the “Green Gap”, is considered a global concern in the LED industry. The polar c-plane orientation of GaN, which is the mainstay in the LED industry, suffers from polarization-induced separation of electrons and hole wavefunctions (also known as the “quantum confined Stark effect”) and low indium incorporation efficiency that ...


Theoretical Studies Of Atomic Transport In Ternary Semiconductor Quantum Dots And Charge Transport In Organic Photovoltaic Active Layers, Xu Han 2016 University of Massachusetts Amherst

Theoretical Studies Of Atomic Transport In Ternary Semiconductor Quantum Dots And Charge Transport In Organic Photovoltaic Active Layers, Xu Han

Doctoral Dissertations May 2014 - current

Ternary semiconductor quantum dots with thermodynamically stable structures are particularly important for achieving optimal performance in optoelectronic and photovoltaic applications. Ternary quantum dots (TQDs) are typically synthesized in the form of core/shell structures. However, misfit strain induced by the abrupt core/shell interface can change the nature of the TQDs dramatically, leading to unstable optoelectronic function. In this thesis, a transient species transport model is developed to predict species distributions in TQDs during their thermal annealing. Specifically, the interdiffusion kinetics is analyzed of group-VI species in ZnSe1-xSx and ZnSe1-xTex TQDs and of group-III ...


Model Systems For Characterizing The Intrinsic Properties Of Polymer Semiconductors: Oligomers And Single Crystals, Nicholas S. Colella 2016 University of Massachusetts Amherst

Model Systems For Characterizing The Intrinsic Properties Of Polymer Semiconductors: Oligomers And Single Crystals, Nicholas S. Colella

Doctoral Dissertations May 2014 - current

Polymer semiconductors hold great promise for the realization of inexpensive, flexible electronic devices. One of the greatest strengths of these materials, their low-cost processability from solution, results in a wide range of solid-state structures. The crystallinity and morphology of these materials strongly impacts their performance as charge carriers. Furthermore, the nature of polymerization inherently leads to the production of materials which are disperse in their molecular character, with regard to both coupling and molecular weight. Thus, it is difficult to deconvolute the intrinsic properties of polymer semiconductors from their synthetic and processing conditions.

Polythiophenes are particularly susceptible to performance variations ...


Solution, Interfacial, And Interlayer Studies Of Electronically Active Polymers, Hsin-Wei Wang 2016 University of Massachusetts - Amherst

Solution, Interfacial, And Interlayer Studies Of Electronically Active Polymers, Hsin-Wei Wang

Doctoral Dissertations May 2014 - current

This thesis describes the solution behavior and interfacial properties of electronically active polymers. The performance of such polymers in devices is often determined by their chain conformation and morphology in solution and in thin films. For example, the intricate balance between polymer domain size and crystalline packing of electron donor and acceptor components, as well as the properties at the polymer-metal interface, are crucial for achieving optimal performance in devices, such as solar cells.

Chapter 1 presents the current progress in polymer-based solar cells, their fundamental principles, and key factors to improve their efficiency. Literature precedents on the development of ...


Photovoltaics: An Investigation Into The Origins Of Efficiency On All Scales, Jeremy Alexander Bannister 2016 Bard College

Photovoltaics: An Investigation Into The Origins Of Efficiency On All Scales, Jeremy Alexander Bannister

Senior Projects Spring 2016

This project is comprised of a set of parallel investigations, which share the common mo- tivation of increasing the efficiency of photovoltaics. First, the reader is introduced to core concepts of photovoltaic energy conversion via a semi-classical description of the phys- ical system. Second, a key player in photovoltaic efficiency calculations, the exciton, is discussed in greater quantum mechanical detail. The reader will be taken through a nu- merical derivation of the low-energy exciton states in various geometries, including a line segment, a circle and a sphere. These numerical calculations are done using Mathematica, a computer program which, due to ...


Turning An Organic Semiconductor Into A Low-Resistance Material By Ion Implantation, Beatrice Fraboni, Alessandra Scidà, Piero Cosseddu, Yongqiang Wang, Michael Nastasi, Silvia Milita, Annalisa Bonfiglio 2015 Università di Bologna

Turning An Organic Semiconductor Into A Low-Resistance Material By Ion Implantation, Beatrice Fraboni, Alessandra Scidà, Piero Cosseddu, Yongqiang Wang, Michael Nastasi, Silvia Milita, Annalisa Bonfiglio

NCESR Publications and Research

We report on the effects of low energy ion implantation on thin films of pentacene, carried out to investigate the efficacy of this process in the fabrication of organic electronic devices. Two different ions, Ne and N, have been implanted and compared, to assess the effects of different reactivity within the hydrocarbon matrix. Strong modification of the electrical conductivity, stable in time, is observed following ion implantation. This effect is significantly larger for N implants (up to six orders of magnitude), which are shown to introduce stable charged species within the hydrocarbon matrix, not only damage as is the case ...


A Platform For Fast Detection Of Let-7 Micro Rna Using Polyaniline Fluorescence And Image Analysis Techniques, Partha P. Sengupta 2015 University of Southern Mississippi

A Platform For Fast Detection Of Let-7 Micro Rna Using Polyaniline Fluorescence And Image Analysis Techniques, Partha P. Sengupta

Master's Theses

The project describes a new strategy for transducing hybridization events through modulating intrinsic properties of the electroconductive polymer polyaniline (PANI). When DNA based probes electrostatically interact with PANI, its fluorescence properties are increased, a phenomenon that can be enhanced by UV irradiation. Hybridization of target nucleic acids results in dissociation of probes causing PANI fluorescence to return to basal levels. By monitoring restoration of base PANI fluorescence as little as 10-11 M (10 pM) of target oligonucleotides could be detected within 15 minutes of hybridization. Detection of complementary oligos was specific, with introduction of a single mismatch failing to ...


Ellipsometric Characterization Of Silicon And Carbon Junctions For Advanced Electronics, Alexander G. Boosalis 2015 University of Nebraska-Lincoln

Ellipsometric Characterization Of Silicon And Carbon Junctions For Advanced Electronics, Alexander G. Boosalis

Theses and Dissertations from Electrical & Computer Engineering

Ellipsometry has long been a valuable technique for the optical characterization of layered systems and thin films. While simple systems like epitaxial silicon dioxide are easily characterized, complex systems of silicon and carbon junctions have proven difficult to analyze. Traditional model dielectric functions for layered silicon homojunctions, a system with a similar structure to modern transistors, often have correlated parameters during ellipsometric data analysis. Similarly, epitaxial graphene as grown from thermal sublimation of silicon from silicon carbide or through chemical vapor deposition, tend to have model dielectric function parameters that correlate with the optical thickness of the graphene due to ...


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