Bulletin of the American Physical Society
2016 Fall Meeting of the APS Ohio-Region Section
Volume 61, Number 12
Friday–Saturday, October 7–8, 2016; Bowling Green, Ohio
Session C1: Novel Materials for Energy and Environment I |
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Chair: Pavel Moroz, Bowling Green State University Room: 201 A |
Saturday, October 8, 2016 9:30AM - 9:42AM |
C1.00001: Computing the Net Optical Force on Molecules Using Cubal Constant Arjun Krishnappa Calculating the net optical force (Gaussian beam) on molecules that are enclosed by a sphere, requires rigorous mathematical steps and consumes more time.~ Also it is complex to compute the total force on molecules that are on a sphere.~ As a result the easy approximate way of calculating the net force is by assuming the sphere as a cube, which reduces the complexity.~ One disadvantage with this method is that the net force is not the actual force, but the approximated force.~ Interestingly, this research has determined a constant that relates the sphere and cube called ``Cubal Constant.''~ Based on this constant, two laws have been proposed: Cubal Volume Law and Cubal Surface Law.~ Cubal Volume Law can be used for determining the net force on molecules in the sphere, whereas Cubal Surface Law is used to compute the force on molecules which are on the sphere.~ Using these two laws, the exact net force on molecules which are in/on the sphere can be calculated by just calculating the force on molecules which are in/on the cube.~ These two laws ~can be ~treated as force laws, so this can be extended to many other applications that involve forces. The constant and laws are theoretically and experimentally verified. [Preview Abstract] |
Saturday, October 8, 2016 9:42AM - 9:54AM |
C1.00002: Elucidating the Degradation Mechanism of Perovskite Solar Cells in Humid Air Zhaoning Song, Suneth Watthage, Geethika Liyanage, Adam Phillips, Michael Heben Solar cells based on organic-inorganic hybrid metal halide perovskites have rapidly progressed over the past few years. With \textgreater 22{\%} power conversion efficiencies, simple fabrication processes, and low manufacturing costs, there is a great potential to proceed towards commercialization. However, perovskite solar cells are currently limited by the instabilities in the materials and devices, especially due to reactions with water. To address this issue, it is important to know why the perovskite materials are unable to retain the excellent optoelectronic properties after exposure to moisture. Here, we investigate water induced device degradation by in-situ mapping the spatial and temporal evolution of laser beam induced current (LBIC) [1]. We show that the hydration of the perovskite phase leads to a significant drop in the external quantum efficiency. However, this process is reversible: drying the device can convert the hydrated phases back to an unhydrated perovskite and recover the desired optoelectronic properties. Understanding of the phase stability and device performance on a microscopic level gives insight toward improving the long-term stability. [1] Song et al., Adv Energy Mater, 1600846, 2016. [Preview Abstract] |
Saturday, October 8, 2016 9:54AM - 10:06AM |
C1.00003: Charge Carrier Dynamics in Perovskite Solar Cells Utilizing C60-SAM Passivated SnO2 Electron Selective Layer or Pb(SCN)2 Additive. Niraj Shrestha, Changlei Wang, Yue Yu, Corey Grice, Weiqiang Liao, Alexander Cimaroli, Jing Chen, Dewei Zhao, Zhenhua Yu, Pei Liu, Nian Cheng, Xingzhong Zhao, Khagendra Bhandari, Paul Roland, Yanfa Yan, Randall Ellingson Photoluminescence measurement was performed to study the effect of various electron selective layers in MAPbI3 perovskite. We observed that significant improvement in electron extraction can be achieved by modifying MAPbI3/SnO2 interface with C60-SAM. Greater PL quenching was observed in MAPbI3/C60-SAM/SnO2/FTO than MAPbI3/SnO2/FTO. PL dynamics were found to be shortened in case of MAPbI3/C60-SAM/SnO2/FTO. These results revealed that photogenerated electrons are extracted at faster rate in MAPbI3/C60-SAM/SnO2/FTO and thereby improving the cell performance. In a separate system, Cs incorporation in FAPbI3 has been found to suppress formation of yellow phase that improves thermal stability of FA1-xCsxPbI3. Enhanced grain size and higher intrinsic photogenerated carrier life time was correlated with the use of Pb(SCN)2 as an additive in FA1-xCsxPbI3, and incorporation of Pb(SCN)2 enabled improved power conversion efficiency. [Preview Abstract] |
(Author Not Attending)
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C1.00004: PVA:LiClO4: a robust, high Tg polymer electrolyte for adjustable ion gating of 2D materials Erich Kinder, Susan Fullerton Polymer electrolytes are an effective way to gate organic semiconductors and nanomaterials, such as nanotubes and 2D materials, by establishing an electrostatic double layer with large capacitance. Widely used solid electrolytes, such as those based on polyethylene oxide, have a glass transition temperature below room temperature. This permits relatively fast ion mobility at T $=$ 23 C, but requires a constant applied field to maintain a doping profile. Moreover, PEO-based electrolytes cannot withstand a variety of solvents, limiting its use. Here, we demonstrate a polymer electrolyte using polyvinyl alcohol (PVA) with Tg \textgreater 23 C, through which a doping profile can be defined by a potential applied when the polymer is heated above Tg, then ``locked-in'' by cooling the electrolyte to room temperature (\textless Tg) to limit ion mobility. Current-voltage measurements of a graphene field effect transistor verify the ``lock-in'' process, showing constant drain current regardless of the applied electrolyte gate bias. Hall bar measurements are used to quantify the charge carrier density. Owing to PVA's chemical stability, photolithography can be performed directly on the polymer electrolyte, which allows for the deposition of a patterned, metal gate directly on the electrolyte, as well as the ability to pattern the electrolyte itself. [Preview Abstract] |
Saturday, October 8, 2016 10:18AM - 10:30AM |
C1.00005: Investigating the Electronic and Structural Properties of Stanene Brendan Ferris, Antonio Cancio We investigate the structural and electronic properties of two-dimensional tin, or stanene, under compressive and tensile strain using density functional theory (DFT). We investigate optimized lattice parameters for several variant structures found in the literature, and the effects of strain on the band structure. Stanene is among a class of atomically thin materials, similar to that of graphene, with a buckled honeycomb-like structure. They are a potential candidate for a quantum spin hall (QSH) insulator in which a quantum hall effect is generated in the absence of a magnetic field due to strong spin-orbit coupling (SOC). A combination of a QSH effect and strain tuneable band gap make stanene an interesting material for spintronic applications. We use ABINIT, a plane-wave pseudo-potential DFT code that accurately reproduces all-electron calculations of ground-state energies and densities, and which can be used to determine the ground state atomic structure. This then enables simple excited state properties like band structure and band gap estimations to be calculated. Strain is applied by fixing atoms in close-to-equilibrium positions. [Preview Abstract] |
Saturday, October 8, 2016 10:30AM - 10:42AM |
C1.00006: Inhomogeneous Single-Molecule Interfacial Electron Transfer Dynamics: A Single-Molecule Approach V. Govind Rao, B. Dhital, H. P. Lu Interfacial electron transfer (ET) plays a critical role in energy science, photocatalysis, and surface chemistry. The inherent complexity of the interfacial ET dynamics is often difficult to resolve by conventional ensemble-averaged spectroscopic or electrochemical measurements alone. Single-molecule spectroscopy provides insightful details about interfacial ET dynamics which are beyond the realms of conventional ensemble-averaged analyses; particularly with regard to complex mechanism and spatiotemporal heterogeneity. Combination of single-molecule fluorescence spectroscopy approach with various other techniques such as atomic force microscopy, electrochemistry, and Raman spectroscopy can further facilitate inspection of multiple-parameters with high chemical selectivity and wide temporal and spatial resolutions. We have used photonstamping spectroscopy correlated with electrochemical techniques to dissect complex interfacial ET dynamics by probing individual Zn-porphyrin molecule anchored to TiO$_{\mathrm{2}}$ NP surface in aqueous electrolyte solution while electrochemically controlling the energy states of TiO$_{\mathrm{2}}$ NPs. Our work advanced a critical understanding of the interfacial ET dynamics by revealing the intermittency of ET dynamics. [Preview Abstract] |
Saturday, October 8, 2016 10:42AM - 10:54AM |
C1.00007: TBD Remy Beaulac |
Saturday, October 8, 2016 10:54AM - 11:06AM |
C1.00008: Catalytic Reductions Promoted by Solar Devices Ruwani Wasalathanthri, Naheya Su, Samuel Jeffrey, Dean Giolando Depletion of fossil fuels is a major issue, thus there is a need for society to develop alternative energy sources. Dihydrogen has been identified as a good alternate energy carrier. The majority of methods of producing dihydrogen depend on fossil fuels, which is a finite and non-renewable resource. This also results in the release of carbon dioxide that causes harmful environmental impacts. Solar-driven dihydrogen production through water splitting offers a better choice as both solar energy and water are renewable and it is a non-polluting process. However, this method still needs highly active non-noble catalysts to drive the reaction efficiently. This research examines the catalytic activity of nickel-based catalysts for the Hydrogen Evolution Reaction (HER). Nickel and nickel phosphide were electroplated onto copper substrates and their catalytic activity was compared with Platinum, which is one of the best catalysts for HER. The nickel phosphide catalyst investigated in this research is shown to have good activity and long term stability in acidic medium. The final aim is to apply these catalysts on the back side of the photovoltaic cell, where the reduction of water to hydrogen occurs, and to develop an efficient system for dihydrogen production. [Preview Abstract] |
Saturday, October 8, 2016 11:06AM - 11:18AM |
C1.00009: Low Cost Corrosion Resistant Water Oxidation Electrodes Kelly Lambright, Christopher Alexander, Derrick Barenbrugge, Dean Giolando Hydrogen gas produced via water splitting has the potential to be an energy source free of emissions. The oxidation half reaction of water splitting has a high energy cost and can be very corrosive towards inexpensive electrode materials and therefore, electrodes consisting of expensive and rare platinum are generally used. This research focuses on both deposition of fluorine doped tin oxide (FTO) as a layer imparting protection against corrosion for inexpensive electrode materials and lowering the overpotential associated with water oxidation using first row transition metal based catalysts. These FTO thin films were deposited onto stainless steel and glass via spray pyrolysis deposition technique employing dibutyltin diacetate or tin tetrachloride with ammonium bifluoride in 200 proof ethanol as the spray solution. Metal salts or metal nanoparticles were added to the spray solution for deposition with the FTO layer. The resultant thin films were characterized using UV-Vis-NIR transmission spectroscopy, two-point probe resistance measurements, scanning electron microscopy, energy dispersive X-ray spectroscopy, and linear sweep voltammetry. The thin film's corrosion resistance was tested via long-term electrolysis studies and coats lasted for as long as 94 days. [Preview Abstract] |
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