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Wearable Piezotronic Devices For Heart Rate Monitoring, Adam J. Miller, Wenzhuo Wu Dr. 2016 Purdue University

Wearable Piezotronic Devices For Heart Rate Monitoring, Adam J. Miller, Wenzhuo Wu Dr.

The Summer Undergraduate Research Fellowship (SURF) Symposium

Self-powered multifunctional wearable devices that are capable of human-device interfacing are highly desired. Piezotronic devices utilize piezoelectricity and semiconductor properties to enable devices to have seamless interaction between human and device. One important use for piezotronic devices is for pressure sensing. Pressure sensing devices have been employed in smart skins, biomonitoring, gesture recognition, and many more applications. This study aims to create a flexible piezotronic device, specifically for use in pressure sensing to monitor heart rate. ZnO nanowires are grown on a flexible polymer substrate so that they can be made into wearable devices. A p-n heterojunction is formed by ...


Photonicstd-2d: Modeling Light Scattering In Periodic Multilayer Photonic Structures, Alexey Bondarev, Shaimaa Azzam, Zhaxylyk Kudyshev, Alexander V. Kildishev 2016 North Carolina State University at Raleigh

Photonicstd-2d: Modeling Light Scattering In Periodic Multilayer Photonic Structures, Alexey Bondarev, Shaimaa Azzam, Zhaxylyk Kudyshev, Alexander V. Kildishev

The Summer Undergraduate Research Fellowship (SURF) Symposium

Efficient modeling of electromagnetic processes in optical and plasmonic metamaterials is important for enabling new and exciting ways to manipulate light for advanced applications. In this work, we put together a tool for numerical simulation of propagation of normally incident light through a nanostructured multilayer composite material. The user builds a unit cell of a given material layer-by-layer starting from a substrate up to a superstrate, splitting each layer further into segments. The segments are defined by width and material -- dielectric, metal or active medium. Simulations are performed with the finite difference time domain (FDTD) method. A database of common ...


Large Scale Monolithic Solar Panel Simulation - A Study On Partial Shading Degradation, Suhas V. Baddela, Xingshu Sun, Muhammad A. Alam 2016 Purdue University

Large Scale Monolithic Solar Panel Simulation - A Study On Partial Shading Degradation, Suhas V. Baddela, Xingshu Sun, Muhammad A. Alam

The Summer Undergraduate Research Fellowship (SURF) Symposium

Shadow-induced degradation is a major concern for both power output and long-term reliability in solar cells. Apart from the obvious fact that shading reduces the amount of solar irradiance available to solar panels, it may lead to formation of hot spots, where solar cells are forced to reverse breakdown with localized heating, and potentially, permanent damage. To get a better understanding of shadow-induced degradation, we develop an electro-thermal coupled simulator that can self-consistently solve the electrical and thermal distributions of solar panel under arbitrary shading conditions. The simulation framework consists of two part: a) compact models that can describe the ...


Interaction Between Charge-Transfer States Studied By Magnetic Field Effects, Mingxing Li 2016 University of Tennessee, Knoxville

Interaction Between Charge-Transfer States Studied By Magnetic Field Effects, Mingxing Li

Doctoral Dissertations

Organic semiconducting materials, consisting mostly of carbon and hydrogen atoms, provide remarkable promise for electronic applications due to their easy processing, chemical tenability, low costs and environmental-friendly characteristics. For realizing electronic applications such as light emitting diodes and photovoltaic cells, charge-transfer states act as an important intermediate state for recombination and dissociation. Interestingly, magnetic field effects on semiconducting materials have been realized based on the suppression of spin mixing in the charge-transfer states. Although lots of studies have been carried out on investigating the properties of charge-transfer states, little has been done to consider the interaction between them. This thesis ...


Material And Process Engineering For Bulk Single Crystal Growth Of High Performance Scintillator Potassium Calcium Iodide, Adam Coleman Lindsey 2016 University of Tennessee, Knoxville

Material And Process Engineering For Bulk Single Crystal Growth Of High Performance Scintillator Potassium Calcium Iodide, Adam Coleman Lindsey

Doctoral Dissertations

Protection against threats of nuclear terrorism relies on the deployment of an enormous number of radiation detection devices with energy resolution to differentiate the radiological signatures of special nuclear materials amongst naturally occurring radiation and other nuisance sources. The capabilities of these devices rely upon the availability of high performance scintillator and semiconductor materials which provide useful responses in the presence of radiation. So far, few materials have been developed to a level that can supplant the use of underperforming NaI:Tl [thallium doped sodium iodide] crystals in the field due to their high cost and/or low yields of ...


Exploring Thermoelectric Effect Based On Multi-Layer Conductor/Organic/Conductor Devices, Qing Liu 2016 University of Tennessee, Knoxville

Exploring Thermoelectric Effect Based On Multi-Layer Conductor/Organic/Conductor Devices, Qing Liu

Doctoral Dissertations

Thermoelectric phenomena involve the simultaneous presence of both electrical and thermal currents. The entropy has been heavily used as the driving force to diffuse charge carriers between high and low temperature surfaces towards the development of Seebeck effects in thermoelectric devices. However, this driving force from entropy difference can cause an inverse relationship between Seebeck coefficient and electrical conductivity in the thermoelectric developments. Increasing the charge density can decrease the entropy difference to diffuse the charge carriers at a given temperature difference and lead to a decrease on the Seebeck coefficient developed by the entropy difference. Therefore, it is necessary ...


Contact Radius And Insulator-Metal Transition In Films Comprised Of Touching Semiconductor Nanocrystals, Deanna M. Lanigan 2016 Washington University in St. Louis

Contact Radius And Insulator-Metal Transition In Films Comprised Of Touching Semiconductor Nanocrystals, Deanna M. Lanigan

Engineering and Applied Science Theses & Dissertations

Nanocrystal assemblies are being explored for a number of optoelectronic applications such as transparent conductors, photovoltaic solar cells, and electrochromic windows. Majority carrier transport is important for these applications, yet it remains relatively poorly understood in films comprised of touching nanocrystals. Specifically, the underlying structural parameters expected to determine the transport mechanism have not been fully elucidated. In this report, we demonstrate experimentally that the contact radius, between touching heavily doped ZnO nanocrystals, controls the electron transport mechanism. Spherical nanocrystals are considered, which are connected by a circular area. The radius of this circular area is the contact radius. For ...


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 ...


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 ...


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 ...


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, 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 ...


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 ...


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 ...


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 ...


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 ...


Synthesis Of Titania Thin Films With Controlled Mesopore Orientation: Nanostructure For Energy Conversion And Storage, Suraj R. Nagpure 2016 University of Kentucky

Synthesis Of Titania Thin Films With Controlled Mesopore Orientation: Nanostructure For Energy Conversion And Storage, Suraj R. Nagpure

Theses and Dissertations--Chemical and Materials Engineering

This dissertation addresses the synthesis mechanism of mesoporous titania thin films with 2D Hexagonal Close Packed (HCP) cylindrical nanopores by an evaporation-induced self-assembly (EISA) method with Pluronic surfactants P123 and F127 as structure directing agents, and their applications in photovoltaics and lithium ion batteries. To provide orthogonal alignment of the pores, surface modification of substrates with crosslinked surfactant has been used to provide a chemically neutral surface. GISAXS studies show not only that aging at 4°C facilitates ordered mesostructure development, but also that aging at this temperature helps to provide orthogonal orientation of the cylindrical micelles which assemble into ...


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