Thienoisatin Oligomers As N-Type Molecular Semiconductors, 2018 Purdue University
Thienoisatin Oligomers As N-Type Molecular Semiconductors, Natalie M. Kadlubowski, Xuyi Luo, Jianguo Mei
The Summer Undergraduate Research Fellowship (SURF) Symposium
Organic field effect transistors (OFETs) offer many advantages compared to traditional inorganic transistors, such as flexibility and solution processability. In this study we design and synthesize two thienoisatin-based organic semiconducting small molecules, then investigate their electronic properties in n-type OFETs. To introduce n-type charge transport, electron-withdrawing dicarbonitrile moieties were installed on thienoisoindigo and bis-thienoisatin molecules, which led to a quinoidal conjugation on thienoisoindigo, while maintaining an aromatic conjugation on the bis-thienoisatin. Following the syntheses, the molecules were characterized to determine highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) levels via cyclic voltammetry, as well as any potential ...
Application Of Nano-Plasmonics For Sers Bio-Detection And Photocatalysis In The Same Platform, 2018 Missouri State University
Application Of Nano-Plasmonics For Sers Bio-Detection And Photocatalysis In The Same Platform, Muhammad R. Shattique
MSU Graduate Theses
Nano-biological systems interfacing nano-structured solid surfaces with biological compounds such as oligonucleotides or proteins are highly regarded as enabling materials for biosensing and biocatalysis applications. In particular, nanostructures of noble metals such as gold or silver, when exposed to light, exhibit a phenomenon known as surface plasmon resonance. When a proper metal nanostructure (plasmonic substrate) is exposed to light, very efficient absorption of incoming photons is possible, resulting in a buildup of localized high-energy regions, or “hot-spots”, where energetic carriers or “hot carriers” can be created. These hot-carriers can be used to catalyze desired chemical transformations in materials located nearby ...
Non-Hysteretic First-Order Phase Transition With Large Latent Heat And Giant Low-Field Magnetocaloric Effect, F. Guillou, Arjun K. Pathak, Durga Paudyal, Yaroslav Mudryk, F. Wilhelm, A. Rogalev, Vitalij K. Pecharsky
Materials Science and Engineering Publications
First-order magnetic transitions (FOMTs) with a large discontinuity in magnetization are highly sought in the development of advanced functional magnetic materials. Isosymmetric magnetoelastic FOMTs that do not perturb crystal symmetry are especially rare, and only a handful of material families, almost exclusively transition metal-based, are known to exhibit them. Yet, here we report a surprising isosymmetric FOMT in a rare-earth intermetallic, Eu2In. What makes this transition in Eu2In even more remarkable is that it is associated with a large latent heat and an exceptionally high magnetocaloric effect in low magnetic fields, but with tiny lattice discontinuities and negligible hysteresis. An ...
Modeling Recombination In Solar Cells, 2018 Macalester College
Modeling Recombination In Solar Cells, Paul Chery
Macalester Journal of Physics and Astronomy
Solar cells are a competitive alternative to nonrenewable energy sources such as fossil fuels. However, the efficiency of these devices is limited by photogenerated carrier recombination. We use a finite difference numerical model to study recombination phenomena in the absorber layer of solar cells including alternate recombination models and the effects of spatial distribution of recombination centers. We compare the effect of using the constant lifetime approximation for recombination to the full Shockley-Read-Hall expression in Silicon solar cells and find that the constant lifetime approximation holds for high defect densities but not for high photon flux densities. Finally, we simulate ...
Solar Cell Potential Induced Degradation Sensor, 2018 California Polytechnic State University, San Luis Obispo
Solar Cell Potential Induced Degradation Sensor, Luc Alexandre Tousignant
It is important to maintain Photovoltaic (PV) cells and protect them from damage mechanisms like Potential Induced Degradation (PID), which can contribute to shorter lifespans and lower efficiencies. Current leakage through cell encapsulation can cause charge migration in PV cells that reduces the maximum quantum efficiency, which is the cause of PID. An experiment was setup to determine the feasibility of a non-silicon sensor able to produce similar leakage behavior to traditional PV cells under recorded humidity conditions. Thin sheet metals were encapsulated in EVA, a common PV encapsulant polymer, and mounted in aluminum framing. Three sensors, along with a ...
In Situ Sem Solidification Study Of Ga And Egain: A Characterization Technique For Monitoring The Microstructural Evolution Of Liquid Metals, 2018 California Polytechnic State University, San Luis Obispo
In Situ Sem Solidification Study Of Ga And Egain: A Characterization Technique For Monitoring The Microstructural Evolution Of Liquid Metals, Jeremy Geovann Del Aguila
Scanning electron microscopy (SEM) video recording is used to characterize the solidification of small volumes of 99.999% pure gallium (Ga) and eutectic gallium-indium (eGaIn) under a high vacuum environment. Specimen are superheated to 55℃ using a hot plate, cast into spherical droplets, and cooled in situ by means of a Peltier cooling stage. Special attention is given to the preparation of the specimen prior to viewing because of gallium and its alloys’ nature to form an oxide layer when melted and air cooled. The oxide acts as a skin that inhibits the observation of microstructural features during solidification. Heated ...
Three Speed 3d Printed Magnetic Gear, 2018 Portland State University
Three Speed 3d Printed Magnetic Gear, Robert J. Rutherford
Undergraduate Research & Mentoring Program
Power transmission is traditionally achieved with a mechanical gear. Mechanical gears require maintenance, cause vibration, and have no overload protection. Magnetic gears offer an innovative solution to these drawbacks as they do not require regular maintenance, have no need for lubrication, create very little acoustic noise, have built in overload protection and as a result of these advantages, have a longer lifetime of operation. This research focused upon the design, assembly and demonstration of the magnetic gear concept. The research used a solid works design, 3D printed ABS plastic housing, and use of neodymium magnets and ferromagnetic iron segments.
Voltage-Controlled Deposition Of Nanoparticles For Next Generation Electronic Materials, 2018 Louisiana State University and Agricultural and Mechanical College
Voltage-Controlled Deposition Of Nanoparticles For Next Generation Electronic Materials, Subhodip Maulik
LSU Doctoral Dissertations
This work presents both a feasibility study and an investigation into the voltage-controlled spray deposition of different nanoparticles, namely, carbon nanotubes (CNTs), as well as molybdenum disulfide (MoS2) and tungsten disulfide (WS2) from the transition metal dichalcogenides (TMDCs) family of materials. The study considers five different types of substrates as per their potential application to next-generation device electronics. The substrates selected for this research were: 1) aluminum as a conducting substrate, 2) silicon as a semiconducting substrate, 3) glass, silicon dioxide (SiO2), and syndiotactic poly methyl methacrylate (syndiotactic PMMA) as insulating substrates.
Since the 1990’s, carbon ...
An Examination Of The Au-Ni Phase Diagram For Magneto-Plasmonic Applications, 2018 University of Tennessee, Knoxville
An Examination Of The Au-Ni Phase Diagram For Magneto-Plasmonic Applications, Christopher C. Walker, John Carothers, Michael Roulier, Brandon Rowell
University of Tennessee Honors Thesis Projects
No abstract provided.
Thermoelectrics And Thermoelectric Devices, 2018 Linfield College
Thermoelectrics And Thermoelectric Devices, Benjamin T. Erck
The field of thermoelectrics has many applications, and more are found in everyday systems. From its current studies, it is apparent that improving the figure of merit zT (which defines a good thermoelectric material) is important in the effectiveness of power generation. Another important part of thermoelectrics is the duality of these devices. They can both move heat and generate power, depending on their role in the system. In this thesis research, a process was made to test these thermoelectric relationships for a few Peltier devices in order to understand their efficiencies and what systems they can be applied to.
Design, Fabrication, And Characterization Of Novel Optoelectronic Devices For Near-Infrared Detection, 2018 University of Arkansas, Fayetteville
Design, Fabrication, And Characterization Of Novel Optoelectronic Devices For Near-Infrared Detection, Ahmad Nusir
Theses and Dissertations
Investigating semiconductor materials and devices at the nanoscale has become crucial in order to maintain the exponential development in today’s technology. There is a critical need for making devices lower in power consumption and smaller in size. Nanoscale semiconductor materials provide a powerful platform for optoelectronic device engineers. They own interesting properties which include enhanced photoconductivity and size-tunable interband transitions.
In this research, different types of nanostructures were investigated for optoelectronic devices: nanocrystals, nanowires, and thin-films. First, lead selenide nanocrystals with narrow bandgap were synthesized, size-tailored, and functionalized with molecular ligands for the application of uncooled near-infrared photodetectors. The ...
Glucose Level Estimation Based On Invasive Electrochemical, And Non-Invasive Optical Sensing Methods, 2018 University of Arkansas, Fayetteville
Glucose Level Estimation Based On Invasive Electrochemical, And Non-Invasive Optical Sensing Methods, Sanghamitra Mandal
Theses and Dissertations
The purpose of this research is to design and fabricate sensors for glucose detection using inexpensive approaches. My first research approach is the fabrication of an amperometric electrochemical glucose sensor, by exploiting the optical properties of semiconductors and structural properties of nanostructures, to enhance the sensor sensitivity and response time. Enzymatic electrochemical sensors are fabricated using two different mechanisms: (1) the low-temperature hydrothermal synthesis of zinc oxide nanorods, and (2) the rapid metal-assisted chemical etching of silicon (Si) to synthesize Si nanowires. The concept of gold nano-electrode ensembles is then employed to the sensors in order to boost the current ...
Investigation Of Nanomaterial Based Photovoltaic Panel Packaging Materials, 2018 University of Arkansas, Fayetteville
Investigation Of Nanomaterial Based Photovoltaic Panel Packaging Materials, Xingeng Yang
Theses and Dissertations
In this research, nanomaterial-based packaging materials for photovoltaic (PV) panels are investigated. A hydrophobic/anti-reflective surface coating which not only repels water from the top glass of a PV panel but at the same time reduces its light reflectance is investigated. COMSOL simulation results indicate that taller ellipsoid rod (aspect ratio = 5) reflects less light than shorter rod (aspect ratio = 0.5) in the desired spectrum for solar energy harvest from 400nm-700nm. The addition of a polymer layer on these ellipsoid rods broadens the light incident angle from 23° to 34°, from which light can be efficiently absorbed. Based on ...
Near Bandgap Two-Photon Excited Luminescence Of Inas Quantum Dots, 2018 University of Arkansas, Fayetteville
Near Bandgap Two-Photon Excited Luminescence Of Inas Quantum Dots, Xian Hu
Theses and Dissertations
Semiconductor quantum dots (QDs) confine carriers in three dimensions, resulting in atomic-like energy levels as well as size-dependent electrical and optical properties. Self-assembled III-V QD is one of the most studied semiconductor QDs thanks to their well-established fabrication techniques and versatile optical properties. This dissertation presents the photoluminescence (PL) study of the InAs/GaAs QDs with both above bandgap continuous-wave excitation (one-photon excitation) and below-bandgap pulse excitation (two-photon excitation). Samples of ensemble QDs, single QD (SQD), and QDs in a micro-cavity, all grown by molecular beam epitaxy, are used in this study. Morphology of these samples was examined using atomic ...
Reactive Lamination Of Perovskite Solar Cells., 2018 University of Louisville
Reactive Lamination Of Perovskite Solar Cells., Lyndie Burns
Electronic Theses and Dissertations
Due to the growing demand for energy internationally and the environmental impact of other conventional energy technologies, solar power has been a growing area in the energy landscape. Perovskite research has increased substantially because of the high power conversion efficiencies, up to 22%, with many recent advances in the use of these organic-inorganic hybrid perovskites for photovoltaic cells. However, to bring perovskite solar cells into the industrial world, the overall cost of the manufacturing of the solar cell must be improved to compete with other well-developed photovoltaic technologies. Here is presented an alternative perovskite deposition method for methylammonium lead halide ...
Design, Fabrication, And Characterization Of All-Inorganic Quantum Dot Light Emitting Diodes, 2018 University of Arkansas, Fayetteville
Design, Fabrication, And Characterization Of All-Inorganic Quantum Dot Light Emitting Diodes, Ramesh Vasan
Theses and Dissertations
Quantum dot light emitting diodes are investigated as a replacement to the existing organic light emitting diodes that are commonly used for thin film lighting and display applications. In this, all-inorganic quantum dot light emitting diodes with inorganic quantum dot emissive layer and inorganic charge transport layers are designed, fabricated, and characterized. Inorganic materials are more environmentally stable and can handle higher current densities than organic materials. The device consists of CdSe/ZnS alloyed core/shell quantum dots as the emissive layer and metal oxide charge transport layer. The charge transport in these devices is found to occur through resonant ...
From Flasks To Applications: Design And Optimization Of Giant Quantum Dots Using Traditional And Automated Synthetic Methods, 2018 University of New Mexico
From Flasks To Applications: Design And Optimization Of Giant Quantum Dots Using Traditional And Automated Synthetic Methods, Christina J. Hanson
Nanoscience and Microsystems ETDs
Semiconducting nanocrystals, also known as quantum dots (QDs), that emit light with near-unity quantum yield and are extremely photostable are attractive options as down-conversion and direct electricity-to-light materials for a variety of applications including solid-state lighting, display technologies, bio-imaging and optical tracking. Standard QDs with a core/thin shell structure display fluorescence intermittency (blinking) and photobleaching when exposed to prolonged room temperature excitation for single dot measurements, as well as significant reabsorption and energy transfer when densely packed into polymers or at high solution concentrations.
We have developed thick shell “giant” QDs (gQDs), ultra-stable photon sources both at the ensemble ...
Characterization Of Magnetic Thin Films Using The Magneto Optic Kerr Effect, 2018 Lynchburg College
Characterization Of Magnetic Thin Films Using The Magneto Optic Kerr Effect, Nicholas J. Savino
Student Scholar Showcase
Understanding magnetic properties of materials allows for advances in applications such as data storage. The Magneto-Optic Kerr Effect (MOKE) displays the reflective response a magnetic material has to a magnetic field. When polarized light reflects off of a magnetic material, the polarization orientation can change. The application of an external magnetic field can affect how much this polarization changes in a non-linear manner. Hysteresis loops are created when examining the relationship between intensity of the reflected light to the applied magnetic field provide information about magnetic properties of that material, such as the coercive field and field retention. Preliminary measurements ...
Swelling As A Stabilizing Mechanism During Ion Bombardment Of Thin Films: An Analytical And Numerical Study, 2018 Southern Methodist University
Swelling As A Stabilizing Mechanism During Ion Bombardment Of Thin Films: An Analytical And Numerical Study, Jennifer M. Swenson
Mathematics Theses and Dissertations
Irradiation of semiconductor surfaces often leads to the spontaneous formation of rippled structures at certain irradiation angles. However, at high enough energies, these structures are observed to vanish for all angles, despite the absence of any identified, universally-stabilizing physical mechanisms in operation. Here, we examine the effect on pattern formation of radiation-induced swelling, which has been excluded from prior treatments of stress in irradiated films. After developing a suitable continuum model, we perform a linear stability analysis to determine its effect on stability. Under appropriate simplifying assumptions, we find swelling indeed to be stabilizing at wavenumbers typical of experimental observations ...
Structural, Transport, And Topological Properties Induced At Complex-Oxide Hetero-Interfaces, 2018 University of Kentucky
Structural, Transport, And Topological Properties Induced At Complex-Oxide Hetero-Interfaces, Justin K. Thompson
Theses and Dissertations--Physics and Astronomy
Complex-oxides have seen an enormous amount of attention in the realm of Condensed Matter Physics and Materials Science/Engineering over the last several decades. Their ability to host a wide variety of novel physical properties has even caused them to be exploited commercially as dielectric, metallic and magnetic materials. Indeed, since the discovery of high temperature superconductivity in the “Cuprates” in the late 1980’s there has been an explosion of activity involving complex-oxides. Further, as the experimental techniques and equipment for fabricating thin films and heterostructures of these materials has improved over the last several decades, the search for ...