Molecular Helices As Electron Acceptors In High-Performance Bulk Heterojunction Solar Cells,
2015
Columbia University
Molecular Helices As Electron Acceptors In High-Performance Bulk Heterojunction Solar Cells, Yu Zhong, M. Tuan Trinh, Rongsheng Chen, Geoffrey E. Purdum, Petr P. Khlyabich, Melda Sezen, Seokjoon Oh, Haiming Zhu, Brandon Fowler, Boyuan Zhang, Wei Wang, Chang-Yong Nam, Matthew Y. Sfeir, Charles T. Black, Michael L. Steigerwald, Yueh-Lin Loo, Fay Ng, X.-Y. Zhu, Colin Nuckolls
Publications and Research
Despite numerous organic semiconducting materials synthesized for organic photovoltaics in the past decade, fullerenes are widely used as electron acceptors in highly efficient bulk-heterojunction solar cells. None of the non-fullerene bulk heterojunction solar cells have achieved efficiencies as high as fullerene-based solar cells. Design principles for fullerene-free acceptors remain unclear in the field. Here we report examples of helical molecular semiconductors as electron acceptors that are on par with fullerene derivatives in efficient solar cells. We achieved an 8.3% power conversion efficiency in a solar cell, which is a record high for non-fullerene bulk heterojunctions. Femtosecond transient absorption spectroscopy revealed …
Characterization Of Point Defects In Lithium Aluminate (Lialo2) Single Crystals,
2015
Air Force Institute of Technology
Characterization Of Point Defects In Lithium Aluminate (Lialo2) Single Crystals, Maurio S. Holston
Theses and Dissertations
Lithium aluminate (LiAlO2) is an insulating wide-band gap material currently under development for tritium breeding and radiation detection and dosimetry applications. Point defects are imperfections in a crystal lattice localized over a few atomic lengths that can alter the electrical, mechanical, or optical properties of materials. An understanding of point defect behavior is a necessary precursor for optimizing lithium aluminate for nuclear applications. This dissertation has identified and characterized the major point defects created and induced through x-ray and neutron radiation using electron paramagnetic resonance and fluorescence spectroscopy, thermoluminescence, and optical absorption. This dissertation explains for the first …
Environmental Degradation Of Nickel-Based Superalloys Due To Gypsiferous Desert Dusts,
2015
Air Force Institute of Technology
Environmental Degradation Of Nickel-Based Superalloys Due To Gypsiferous Desert Dusts, Matthew B. Krisak
Theses and Dissertations
More than twenty-five years of continuous operation in the dusty environments of Southwest Asia have shown that degradation of gas turbine engine components due to particle ingestion is a serious threat to operations. In particular, the continued push for higher engine operating temperatures has brought a new emphasis to the damage mechanisms (for example CMAS glass formation and hot corrosion) caused by ingested particles forming molten deposits on engine components. Despite decades of research little progress has been made to mitigate the effects of CMAS and hot corrosion degradation to engine components. This research focused on hot corrosion specifically. A …
Bio-Photoelectrochemical Solar Cells Incorporating Reaction Center And Reaction Center Plus Light Harvesting Complexes,
2015
University of South Florida
Bio-Photoelectrochemical Solar Cells Incorporating Reaction Center And Reaction Center Plus Light Harvesting Complexes, Houman Yaghoubi
USF Tampa Graduate Theses and Dissertations
Harvesting solar energy can potentially be a promising solution to the energy crisis now and in the future. However, material and processing costs continue to be the most important limitations for the commercial devices. A key solution to these problems might lie within the development of bio-hybrid solar cells that seeks to mimic photosynthesis to harvest solar energy and to take advantage of the low material costs, negative carbon footprint, and material abundance. The bio-photoelectrochemical cell technologies exploit biomimetic means of energy conversion by utilizing plant-derived photosystems which can be inexpensive and ultimately the most sustainable alternative. Plants and photosynthetic …
Ductility And Use Of Titanium Alloy And Stainless Steel Aerospace Fasteners,
2015
University of South Florida
Ductility And Use Of Titanium Alloy And Stainless Steel Aerospace Fasteners, Jarrod Talbott Whittaker
USF Tampa Graduate Theses and Dissertations
The main purpose of this thesis is to investigate the ductility and application of titanium alloys, like titanium 6Al-4V, when used in aerospace fasteners compared to more conventional stainless steel aerospace fasteners such as A286. There have been concerns raised about the safe usability of titanium 6-4 in the aerospace industry due to its lack of strain hardening. However, there is a lack of data pertaining to this concern of safe usage which this thesis aims to address. Tensile tests were conducted to find the ductility indexes of these fasteners which quantify the amount of plastic to elastic elongation. From …
An Investigation On The Band Gap And Band Edge Of Semi-Conducting Lanthanum Transition Metal Perovskites For Photocatalytic Applications,
2015
University of South Florida
An Investigation On The Band Gap And Band Edge Of Semi-Conducting Lanthanum Transition Metal Perovskites For Photocatalytic Applications, Divya Suresh
USF Tampa Graduate Theses and Dissertations
For the past few decades, a frenzy of attention has been given towards the development of an assortment of photocatalysts as a solution for various environmental problems. TiO2 is the most widely used photocatalyst. TiO2 is biocompatible, chemically and thermally stable but TiO2 and a vast majority other photocatalysts have large band gaps, and hence they find applicability only in the UV region of the solar spectrum. These large band gap photocatalysts suffer a severe limitation with regard to their overall process efficiency as the UV region contributes to about 3 to 4 % of the solar spectrum in terms …
Molexpl: A Tool For Ab Initio Data Exploration And Visualization,
2015
Purdue University
Molexpl: A Tool For Ab Initio Data Exploration And Visualization, Xueying Wang, Nicolas Onofrio, Alejandro Strachan
The Summer Undergraduate Research Fellowship (SURF) Symposium
Density functional theory (DFT) based on ab initio theory, is a powerful method to resolve the electronic structure of atoms, molecules and solids. However, in practical, DFT is limited to few hundreds of atoms. To overcome this limitation, researchers have developed empirical interatomic potentials implemented in molecular dynamics (MD) simulations. MD ignores the movements of electrons and describes bonding and non-bonding interaction as a function of the distance between atoms called force fields (FF) or interatomic potentials. These empirical potentials are optimized against large datasets of DFT calculations relevant to describe the interactions between the atoms included in the training …
Long-Term Stability Of 14yt-4sc Alloy At High Temperature,
2015
North Carolina State University at Raleigh
Long-Term Stability Of 14yt-4sc Alloy At High Temperature, Lulu Li, Weizong Xu, Mostafa Saber, Yuntian Zhu, Carl C. Koch, Ronald O. Scattergood
Mechanical and Materials Engineering Faculty Publications and Presentations
14YT alloy (Fe-14Cr-0.25wt.%Y2O3-0.4wt.%Ti) with 4 at.% Sc addition was previously reported to exhibit a nanoscale microstructure and high strength when annealed at temperatures up to 1000 °C (0.65Tm) for 1 hour. Here we report that the microstructure and mechanical behavior of 14YT-4Sc alloy after long-term annealing for up to 60 hours at 1000 °C. FIB analysis shows abnormal grain growth with annealing time, while a large fraction of the matrix still consists of nanoscale grains. TEM images reveal a slight growth of nano grains, with estimated grain growth exponent, n, to be 0.29. Sc-Ti-Y-O enriched nano oxide particles (nm) were …
Characterization Of Iron Phthalocyanine As The Cathode Active Material For Lithium-Ion Batteries,
2015
University of Dayton
Characterization Of Iron Phthalocyanine As The Cathode Active Material For Lithium-Ion Batteries, Sarwan S. Sandhu, Joseph P. Fellner
Chemical and Materials Engineering Faculty Publications
The developed thermodynamic functions for the determination of Gibbs free energy, enthalpy, and entropy of formation of solid lithium-iron phthalocyanine (LixFePc) from solid lithium and iron phthalocyanine as a function of x, defined as g-moles of the intercalated lithium per g-mole of iron phthalocyanine, at a fixed set of temperature and pressure conditions are presented. In addition, a proposed expression for the evaluation of lithium diffusion coefficient in solid iron phthalocyanine as a function of both x and temperature, and the experimental results from the ongoing research/development work on the lithium/iron phthalocyanine cells are included.
Stability And Decomposition Of Ca-Substituted Lanthanum Ferrite In Reducing Atmospheres,
2015
Boise State University
Stability And Decomposition Of Ca-Substituted Lanthanum Ferrite In Reducing Atmospheres, Patrick M. Price, Darryl P. Butt
Materials Science and Engineering Faculty Publications and Presentations
Calcium-substituted lanthanum ferrites (La1–xCaxFeO3–δ x = 0, 0.1, 0.2, 0.3, 0.4) were synthesized in air and subsequently decomposed in reducing atmospheres. The partial pressure of oxygen (PO2) was controlled by varying the H2/H2O ratio by bubbling hydrogen/argon mixtures through water baths at controlled temperatures. Three regions of mass loss were identified as the PO2 was reduced, two of which were determined to be associated with decomposition reactions. Calcium was shown to decrease the thermal stability of the perovskite compound, but rather …
The Role Of Biological Fluid And Dynamic Flow In The Behavior And Cellular Interactions Of Gold Nanoparticles,
2015
University of Dayton
The Role Of Biological Fluid And Dynamic Flow In The Behavior And Cellular Interactions Of Gold Nanoparticles, Emily K. Breitner, Saber M. Hussain, Kristen K. Comfort
Chemical and Materials Engineering Faculty Publications
Background: Due to their distinctive physicochemical properties, nanoparticles (NPs) have proven to be extremely advantageous for product and application development, but are also capable of inducing detrimental outcomes in biological systems. Standard in vitro methodologies are currently the primary means for evaluating NP safety, as vast quantities of particles exist that require appraisal. However, cell-based models are plagued by the fact that they are not representative of complex physiological systems. The need for a more accurate exposure model is highlighted by the fact that NP behavior and subsequent bioresponses are highly dependent upon their surroundings. Therefore, standard in vitro models …
Production And Characterization Of Composite Nano/Micro Sized Particles By Rapid Expansion Of Supercritical Solutions (Ress) Co-Precipitation,
2015
New Jersey Institute of Technology
Production And Characterization Of Composite Nano/Micro Sized Particles By Rapid Expansion Of Supercritical Solutions (Ress) Co-Precipitation, Beidi He
Dissertations
Nanoscale composites of hexahydro-1, 3, 5-trinitro-1, 3, 5-triazine (RDX) and polymer binders were produced by co-precipitation using rapid expansion of supercritical solutions (RESS). The binders used in this study are poly (vinylidene fluoride-co-hexafluoropropylene) (VDF-HFP22), polystyrene (PS) and 7-amino-4-methyl coumarin (AMC). The RDX/VDF-HFP22 and RDX/PS co-precipitated nanoparticles were characterized by Field Emission Scanning Electron Microscopy (FE-SEM) and Transmission Electron Microscopy (TEM). The average size of produced nanoparticles is ca. 100 nm. TEM analysis of RDX/PS nano-composite shows a core-shell structure with RDX as the core material and the shell consisting of the polymeric binder. X-ray Powder Diffraction (XRPD) analysis …
Controlling Optical Absorption In Metamaterial Absorbers For Plasmonic Solar Cells,
2015
Michigan Technological University
Controlling Optical Absorption In Metamaterial Absorbers For Plasmonic Solar Cells, Wyatt Adams, Ankit Vora, Jephias Gwamuri, Joshua M. Pearce, Durdo O. Guney
Department of Materials Science and Engineering Publications
Metals in the plasmonic metamaterial absorbers for photovoltaics constitute undesired resistive heating. However, tailoring the geometric skin depth of metals can minimize resistive losses while maximizing the optical absorbance in the active semiconductors of the photovoltaic device. Considering experimental permittivity data for InxGa1-xN, absorbance in the semiconductor layers of the photovoltaic device can reach above 90%. The results here also provides guidance to compare the performance of different semiconductor materials. This skin depth engineering approach can also be applied to other optoelectronic devices, where optimizing the device performance demands minimizing resistive losses and power consumption, such as photodetectors, laser diodes, …
Synthesis, Structure And Electrochemical Performance Of Na2Mnsio4/C Cathode Material For Na-Ion Batteries,
2015
State Key Lab of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, Fujian, China;
Synthesis, Structure And Electrochemical Performance Of Na2Mnsio4/C Cathode Material For Na-Ion Batteries, Shou-Ding Li, Jiang-Huai Guo, Yong Xie, Jin-Xiao Mi, Yong Yang
Journal of Electrochemistry
As a promising cathode material for sodium ion batteries, pure phase Na2MnSiO4/C nanocomposite was successfully synthesized by a sol-gel method with a citric acid as a complex agent. The as prepared material was characterized by XRD, FTIR, SEM and TEM techniques. XRD and Rietveld refinement results indicated that the sample was indexed as monoclinic structure with space group of Pn. It was observed by SEM and TEM that the obtained product consisted of micro-scaled secondary particles, which were composed of NaMnSiO4 nanocrystallites and amorphous carbon network. More importantly, the uniform carbon network in the …
Broadband Sum-Frequency Generation Spectroscopic Invstigations Of Thiocyanate On Polycrystalline Au Electrode In Alkaline Solutions,
2015
State Key Laboratory of Physical Chemistry of Solid Surfaces, The MOE Key Laboratory of Spectrochemical Analysis and Instrumentation, and Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, Fujian, China;
Broadband Sum-Frequency Generation Spectroscopic Invstigations Of Thiocyanate On Polycrystalline Au Electrode In Alkaline Solutions, Mei Xu, Jing-Jing Wang, Zhi-Chao Huangfu, Ng Ying Wa, Yu-Han He, Zhao-Hui Wang
Journal of Electrochemistry
Broadband sum frequency generation (BB-SFG) spectroscopy has been used to investigating the potential-dependent adsorption behaviors of thiocyanate ions on polycrystalline Au electrode in alkaline solutions. During the positive scan, a change in the Stark slope (dωC-N/dE) for C—N stretching mode can be observed in the range of -1.1 V ~ 0.2 V (vs. SCE), which implies that the orientation of adsorbed thiocyanate ions at Au electrode surface changes from N-bound (dωC-N/dE=45 cm-1·V-1) form to S-bound (dωC-N/dE = 16.2 cm-1·V-1 …
Synthesis And Electrochemical Performance Of Mn3O4/Graphene Composites,
2015
State Key Lab of Physical Chemistry of Solid Surfaces, Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, Fujian, China;
Synthesis And Electrochemical Performance Of Mn3O4/Graphene Composites, Shan-Shan Yang, Qian Zhang, Xiong-Gui Lin, Ming-Sen Zheng, Quan-Feng Dong
Journal of Electrochemistry
The Mn3O4/Graphene composites were synthesized by hydrothermal method with the in-situ redox reaction of graphene oxide (GO) and manganese acetate (Mn(Ac)2). The phase structures and morphologies of the materials were characterized by XRD, SEM and TEM. The XPS and IR techniques were used for studying the residual function groups of reduced graphene oxide (RGO). The electrochemical performances of the hybrids were tested in a coin cell. Results showed that the composites prepared with the addition of ammonia water (RM-A) have better performance. The graphenes in RM-A were better-reduced and the Mn3O4 …
Tungsten Carbide/Carbon Electrode Material Synthesized By Block Copolymer Template Method,
2015
State Key Laboratory Breeding Base for Green Chemistry Synthesis Technology, College of Chemical Engineering, Zhejiang University of Technology, Hangzhou 310032, China;College of Chemical and Materials Science, Longyan University, Longyan 364000, Fujian, China;
Tungsten Carbide/Carbon Electrode Material Synthesized By Block Copolymer Template Method, Xiao-Ling Lang, Ye-Kun Jiang, Mei-Qin Shi, Ling-Zhi Kang, Chun-An Ma
Journal of Electrochemistry
At present, one of the major hurdles for commercialization of system with direct methanol fuel cell (DMFC) is still the requirement of a significant amount of platinum (Pt) catalyst to achieve an acceptable power density. Pt and Pt-based metals are expensive due to limited supplies. In order to find the catalyst alternative to the Pt metal, we selected tungsten carbide (WC) and its composites as the study object. We synthesized WC with carbon materials as the suitable support to modify the electronic structure and to increase the specific surface area of WC. In this study, tungsten carbide/carbon (WC/C) was prepared …
Electrochemical Removal Of Low Concentration Pb(Ii) From Aqueous Solution Based On Ppy/α-Zrp/Ptcf Electrode,
2015
Department of Chemical Eegineering, Taiyuan University of Technology, Taiyuan 030024, Shanxi, China;
Electrochemical Removal Of Low Concentration Pb(Ii) From Aqueous Solution Based On Ppy/α-Zrp/Ptcf Electrode, Ru-Yi Chen, Peng-Le Zhang, Sen-Liang Liao, Zhong-De Wang, Xiao-Gang Hao
Journal of Electrochemistry
A novel organic-inorganic hybrid film consisting of polypyrrole/α-zirconium phosphate (PPy/α-ZrP) was prepared in an aqueous phase by cyclic voltammetry method. It was proved by FT-IR, XRD and XPS characterizations that the electroactive PPy/α-ZrP hybrid film was synthesized successfully. The PPy/α-ZrP film electrode prepared on a porous three-dimensional carbon felt (PTCF) was used for removal of a low concentration of Pb(II) ions from an aqueous solution by electrochemically switched ion exchange (ESIX). A quick uptake and release rate of Pb(II) onto the film electrode was obtained by adjusting redox state of the hybrid film. The removal efficiency and adsorption capacity of …
Mechanism Study On The Electrocatalytic Oxidation Of Acetylene To Oxalic Acid,
2015
College of Chemistry and Chemical Engineering, Taiyuan University of Technology, Taiyuan 030024, China; Department of Chemistry, Taiyuan Normal University, Taiyuan 030031, China;
Mechanism Study On The Electrocatalytic Oxidation Of Acetylene To Oxalic Acid, Xiu-Li Song, Rui-Long Jia, Wen-Yan Dong, Zhen-Hai Liang
Journal of Electrochemistry
A new method of electrocatalytic synthesis oxalic acid from acetylene was explored and the synthesized oxalic acid was characterized by Ultraviolet-visible spectrophotometry (Uv-vis) and Infrared spectroscopy (IR). First-principles calculations were carried out to examine the adsorption of acetylene over the Pt(111) surface. The electrocatalytic oxidation behavior of acetylene has been investigated on a Pt electrode by cyclic voltammetry (CV) and steady-state polarization in Na2SO4 solution. The formation mechanism of oxalic acid in the Na2SO4 solution was proposed and the transfer coefficients of the reaction were calculated. The results show that acetylene molecule tends to …
Preparation And Enhanced Rate Capability Of Spinel Limn1.9Al0.1O3.95F0.05,
2015
College of Chemistry and Chemical Engineering, Central South University, Changsha 410083, China;
Preparation And Enhanced Rate Capability Of Spinel Limn1.9Al0.1O3.95F0.05, Jun-Yan Hu, Meng-Meng Wang, Hong-Tao Liu
Journal of Electrochemistry
Spinel LiMn1.9Al0.1O3.95F0.05 cathode materials with good crystallinity were synthesized by a sol-gel process followed with a high-temperature solid reaction. The effects of partial substitution of Al for Mn, and F for O on the structure and the electrochemical performance were investigated. The results showed that LiMn1.9Al0.1O3.95F0.05 exhibited the same crystalline state as LiMn2O4, but much better electrochemical stability at higher rate cycling. As a result, LiMn1.9Al0.1O3.95F0.05 could maintain stable electrochemical lithium storage even suffering from …
