A5072130805- Perovskite Materials and Applications
- Quantum Dots Synthesis And Properties
- Chalcogenide Semiconductor Thin Films
- Electronic and Structural Properties of Oxides
- X-ray Diffraction in Crystallography
- Luminescence Properties of Advanced Materials
- Metal-Organic Frameworks: Synthesis and Applications
- Nuclear materials and radiation effects
- Crystallization and Solubility Studies
- Machine Learning in Materials Science
- Catalytic Processes in Materials Science
- Copper-based nanomaterials and applications
- Semiconductor materials and devices
- Advanced Photocatalysis Techniques
- Inorganic Fluorides and Related Compounds
- Molecular Junctions and Nanostructures
- Transition Metal Oxide Nanomaterials
- CO2 Reduction Techniques and Catalysts
- 2D Materials and Applications
- Nanofabrication and Lithography Techniques
- Economic and Social Issues
- Optical properties and cooling technologies in crystalline materials
- 3D IC and TSV technologies
- Physics and Engineering Research Articles
- Chemical Synthesis and Reactions
Worcester Polytechnic Institute
2016-2020
Bioengineering Center
2019-2020
University of Worcester
2016-2020
There has been an urgent need to eliminate toxic lead from the prevailing halide perovskite solar cells (PSCs), but current lead-free PSCs are still plagued with critical issues of low efficiency and poor stability. This is primarily due their inadequate photovoltaic properties chemical Herein we demonstrate use lead-free, all-inorganic cesium tin-germanium triiodide (CsSn0.5Ge0.5I3) solid-solution as light absorber in PSCs, delivering promising up 7.11%. More importantly, these show very...
Framework nitrogen atoms of carbon nitride (C3N4) can coordinate with and activate metal sites for catalysis. In this study, C3N4 was employed to harvest visible light Co2+ sites, without the use additional ligands, in photochemical CO2 reduction. Photocatalysts containing single on were prepared by a simple deposition method demonstrated excellent activity product selectivity toward CO formation. A turnover number more than 200 obtained production using synthesized photocatalyst under...
Tin-based halide perovskite solar cells (PSCs) hold the most promise among lead-free PSCs, but they are plagued with inadequate environmental stability and power-conversion efficiency (PCE). Here we demonstrate that optimum incorporation of a bulky divalent organic cation, 4-(aminomethyl)piperidinium (4AMP), in FASnI3 thin films improves stability, optoelectronic properties, PSC performance. The optimized yields maximum PCE 10.9% good 500-h operational under continuous illumination. This is...
Dispersed atomic catalysts can achieve high catalytic efficiency and have the potential to enable chemical transformation of inert molecules like CO2. The effect surface defects on photocatalytic reduction CO2 using supported single atom however requires clarification. Using density functional theory experimental techniques, we investigated role oxygen vacancies (Ov) photoexcited electrons Cu reduction. Adsorption was strong TiO2 surface, charges atoms were highly dependent whether present....
Abstract Significant optical absorption in the blue–green spectral range, high intralayer carrier mobility, and band alignment suitable for water splitting suggest tin disulfide (SnS 2 ) as a candidate material photo‐electrochemical applications. In this work, vertically aligned SnS nanoflakes are synthesized directly on transparent conductive substrates using scalable close space sublimation (CSS) method. Detailed characterization by time‐resolved terahertz photoluminescence spectroscopies...
ZSM-5 zeolite degrades the crystal surface framework and internal acid sites, dependent on unique thermophysical nature of water solvent.
Recent reports post conflicting results on the atmospheric stability of Cs2TiBr6, a nontoxic, Earth-abundant solar energy conversion material. Here, high-temperature melt CsBr and TiBr4 yielded large-grain samples with >1 mm2 facets as verified by optical microscopy scanning electron (SEM). With pristine-material properties particular interest, we investigated series physicochemical surface treatments including rinsing, abrasion, cleaving in ultrahigh vacuum (UHV). For each treatment, X-ray...
We enhanced the solar energy conversion efficiency of solution-deposited Bi<sub>2</sub>S<sub>3</sub> by annealing in sulfur vapor at elevated temperature.
We investigated synthetic strategies for the functionalization of Si(111) surfaces with organic species containing amine moieties. employed functionalized to chemically "glue" perovskites silicon efficient electron transfer and minimal oxidation leading deleterious recombination at substrate. A two-step halogenation-alkylation reaction produced a mixed allyl–methyl monolayer on Si(111). Subsequent reactions utilized multiple methods brominating allyl double bond including HBr in acetic acid,...
We quantified the chemical species present at and reactivity of (100) face tetrahedral single-crystal methylammonium lead iodide, MAPbI3(100), polycrystalline cesium tin bromide, CsSnBr3. For these ABX3 perovskites, experiments utilized orthogonal A+-site cation, B2+-site X–-site halide anion. Ambient pressure exposure to BF3 solutions probed interfacial halides. Reactions with p-trifluoromethylanilinium chloride exchange cation. A complex-forming ligand,...
Atomic-scale species (atoms and clusters) have attracted much attention as potential highly active catalysts. Synthesizing such catalysts that may be stable under synthesis or reaction conditions is a challenge. In this work, we used density functional theory to model the growth of Cu clusters on TiO2 support, including sintering oxidation. Oxidation supported was preferred over due metal-support interactions. Ab initio thermodynamics calculations showed O2 readily oxidized most clusters,...
The luminescence of azobenzene chromophore struts in a metal organic framework is quenched by nitroaromatic guests. X-ray photoelectron spectroscopic methods verify the emission changes are due to surface adsorption guest molecules rather than encapsulation.
First synthesis of CuBiW<sub>2</sub>O<sub>8</sub> with direct bandgap 1.9−2.0 eV and characterization photoexcited charge dynamics from picoseconds to nanoseconds.
Through concurrent halide and acid catalysis, olefin-forming dehydrations non-rearranging Friedel–Crafts alkylations under mild conditions are established.
We functionalized chemically oxidized Si(111) and TiO2 surfaces with covalently attached rylene molecules demonstrated further chemical conversion of the species. Base-catalyzed activation perylene tetracarboxylic dianhydride (PTCDA) preceded reaction phenylaminosilane-terminated surfaces, yielding surface-bound via an imide linkage. Transflection infrared (IR) spectroscopy carbonyl vibrational region elucidated presence anhydride, imide, ester species following each stage. The both...
To bridge the gap between cleanliness of a freshly cleaved surface 2D BiOI and that available from purely chemical-etching means, we subjected single-crystal to series treatments quantified resulting chemical states electronic properties. Vapor transport syntheses included both physical vapor single-source BiOI, as well Bi2O3 + BiI3 Bi I2 Bi2O3. Surface tape cleaving, rinsing in water, sonication acetone, an aqueous HF etch, sequential etch with subsequent acetone. X-ray diffraction, XRD,...
Covalently attached perylene monolayers serve as back contacts for Sb2S3 photoelectrochemical cells with a thianthrene+/0 front, rectifying contact. Covalent attachment of perylenetetracarboxylic dianhydride, PTCDA, to Si(111) utilizes an anhydride-to-imide conversion at surface-attached amines. For solar absorbers, we hypothesized that terminal thioperylene anhydride, i.e., S═C–O–C═S, formed from thionation the anhydride would soft, electron-selective and hole-blocking We explored several...
Dual-liquid-junction photoelectrochemistry and finite-element computational modeling quantified the effect on open-circuit photovoltage, Voc, of varying barrier heights at back, traditionally ohmic contact to a semiconductor. Variations in experimental back-contact included changes redox potential energy contacting phase afforded by series nonaqueous, metallocene-based couples that demonstrate facile, one-electron transfer dipole-based band edge shifts due chemical species semiconductor...
A metal organic framework containing an azobenzene chromophore exhibits luminescence that is quenched by nitro-phenol derivatives. The model system was used to develop new analytical approach differentiating between encapsulated guest molecules and those adsorbed on the outside of MOF
A metal organic framework containing an azobenzene chromophore exhibits luminescence that is quenched by nitro-phenol derivatives. The model system was used to develop new analytical approach differentiating between encapsulated guest molecules and those adsorbed on the outside of MOF