A5058916975- Organic Electronics and Photovoltaics
- Conducting polymers and applications
- Molecular Junctions and Nanostructures
- Thin-Film Transistor Technologies
- Advanced Chemical Physics Studies
- Spectroscopy and Quantum Chemical Studies
- Quantum Dots Synthesis And Properties
- Semiconductor materials and devices
- Electron and X-Ray Spectroscopy Techniques
- Catalytic Processes in Materials Science
- Organic Light-Emitting Diodes Research
- Nanowire Synthesis and Applications
- Force Microscopy Techniques and Applications
- Perovskite Materials and Applications
- Electrodeposition and Electroless Coatings
- Advanced Sensor and Energy Harvesting Materials
- Chalcogenide Semiconductor Thin Films
- Analytical Chemistry and Sensors
- Near-Field Optical Microscopy
- Integrated Circuits and Semiconductor Failure Analysis
- Electrochemical Analysis and Applications
- Semiconductor materials and interfaces
- Spectroscopy and Laser Applications
- Transgenic Plants and Applications
- Spectroscopy Techniques in Biomedical and Chemical Research
National Institute of Standards and Technology
2015-2024
Material Measurement Laboratory
2014-2024
National Institute of Standards
2009-2022
NOAA Chemical Sciences Laboratory
2006-2010
University of Maryland, College Park
2006-2009
Physical Sciences (United States)
2009
Rutgers, The State University of New Jersey
2009
Queen Mary University of London
2008
Stanford Synchrotron Radiation Lightsource
2007-2008
Arizona State University
2001-2008
Electrolysis offers an attractive route to upgrade greenhouse gases such as carbon dioxide (CO2) valuable fuels and feedstocks; however, productivity is often limited by gas diffusion through a liquid electrolyte the surface of catalyst. Here, we present catalyst:ionomer bulk heterojunction (CIBH) architecture that decouples gas, ion, electron transport. The CIBH comprises metal superfine ionomer layer with hydrophobic hydrophilic functionalities extend ion transport from tens nanometers...
The optical properties of coupled metallic nanorods are studied to investigate the use plasmonic structures in field-enhanced spectroscopies. Light scattering by is calculated with boundary element method, including retardation. modes nanorod systems charge method and discussed terms their symmetry. Similar behavior for isolated pairs can mask very different local responses that produce near-field enhancement. response rods redshifts increasing rod length because intrarod restoring forces...
Abstract Organic semiconductors are emerging as a viable alternative to amorphous silicon in range of thin‐film transistor devices. With the possibility formulate these p‐type materials inks and subsequently print into patterned devices, organic‐based transistors offer significant commercial advantages for manufacture, with initial applications such low performance displays simple logic being envisaged. Previous limitations both air stability electrical now overcome small molecule...
We describe a series of highly soluble diketo pyrrolo-pyrrole (DPP)-bithiophene copolymers exhibiting field effect hole mobilities up to 0.74 cm(2) V(-1) s(-1), with common synthetic motif bulky 2-octyldodecyl side groups on the conjugated backbone. Spectroscopy, diffraction, and microscopy measurements reveal transition in molecular packing behavior from preferentially edge-on orientation plane face-on as attachment density chains increases. Thermal annealing generally reduces both...
High performance, solution processable semiconductors are critical to the realization of low cost, large area electronics. We show that a signature molecular packing motifside-chain interdigitationcorrelates high performance for and important class organic semiconductors. The side chains recently developed copolymers poly(alkylthiophenes) can do interdigitate substantially, whereas they not in most common form extensively studied, lower poly(alkythiophenes). Side-chain interdigitation...
Abstract A novel method of strain‐aligning polymer films is introduced and applied to regioregular poly(3‐hexylthiophene) (P3HT), showing several important features charge transport. The backbone shown align in the direction strain resulting a large charge‐mobility anisotropy, where in‐plane mobility increases decreases perpendicular direction. In aligned film, hole successfully represented by two‐dimensional tensor, suggesting that transport parallel within P3HT crystal strongly favored...
We report quantitative measurements of ordering, molecular orientation, and nanoscale morphology in the active layer bulk heterojunction (BHJ) organic photovoltaic cells based on a thieno[3,4-b]thiophene-alt-benzodithiophene copolymer (PTB7), which has been shown to yield very high power conversion efficiency when blended with [6,6]-phenyl-C71-butyric acid methyl ester (PC71BM). A surprisingly low degree order was found polymer—far lower than pure PTB7. X-ray diffraction data yielded nearly...
Optimized spin-coating and blade-coating are found to produce similar performance yet notably different morphologies.
Abstract The electroreduction of C 1 feedgas to high-energy-density fuels provides an attractive avenue the storage renewable electricity. Much progress has been made improve selectivity and 2 products, however, desirable 3 products remains relatively low. We reason that electrosynthesis relies on a higher-order reaction pathway requires formation multiple carbon-carbon (C-C) bonds, thus pursue strategy explicitly designed couple with intermediates. develop approach wherein neighboring...
Abstract Organic–inorganic hybrid perovskite solar cells (PSCs) have seen a rapid rise in power conversion efficiencies recent years; however, they still suffer from interfacial recombination and charge extraction losses at interfaces between the absorber charge–transport layers. Here, situ back‐contact passivation (BCP) that reduces hole transport layer (HTL) is reported. A thin of nondoped semiconducting polymer perovskite/HTL interface introduced it shown use semiconductor permits—in...
Abstract Organic photovoltaics based on non-fullerene acceptors (NFAs) show record efficiency of 16 to 17% and increased photovoltage owing the low driving force for interfacial charge-transfer. However, potentially slows down charge generation, leading a tradeoff between voltage current. Here, we disentangle intrinsic charge-transfer rates from morphology-dependent exciton diffusion series polymer:NFA systems. Moreover, establish influence energetics electron hole transfer separately. We...
Colloidal quantum dots (CQDs) are promising materials for infrared (IR) light detection due to their tunable bandgap and solution processing; however, date, the time response of CQD IR photodiodes is inferior that provided by Si InGaAs. It reasoned high permittivity II-VI CQDs leads slow charge extraction screening capacitance, whereas III-Vs-if surface chemistry can be mastered-offer a low thus increase potential high-speed operation. In initial studies, it found covalent character in...
We present a novel procedure for vibrationally resolved sum-frequency generation (SFG) in which broad-bandwidth IR pulse is mixed with narrow-bandwidth visible pulse. The resultant SFG spectrum dispersed spectrograph and detected parallel scientific-grade CCD detector, permitting rapid high signal-to-noise ratio data acquisition over 400-cm(-1) spectral region without scanning the frequency. Application to study of self-assembled monolayer octadecanethiol discussed.
Oral immunogenicity of recombinant hepatitis B surface antigen (HBsAg) derived from yeast (purified product) or in transgenic potatoes (uncooked unprocessed sample) was compared. An oral adjuvant, cholera toxin, used to increase immune responses. Transgenic plant material containing HBsAg the superior means both inducing a primary response and priming mice respond subsequent parenteral injection HBsAg. Electron microscopy samples revealed evidence that accumulated intracellularly; we...
The structure within crystalline thin films of a high-carrier-mobility polythiophene is studied with complementary characterization methods and first-principles theory. As shown in the figure, two important structural aspects are revealed: 1) slip face-to-face π-π packing, which strongly influences carrier mobility, 2) interdigitation highly trans side chains between vertically adjacent lamellae.
A double-blind placebo-controlled clinical trial evaluated the immunogenicity of hepatitis B surface antigen (HBsAg) expressed in potatoes and delivered orally to previously vaccinated individuals. The accumulated HBsAg at ≈8.5 μg/g potato tuber, doses 100 g tuber were administered by ingestion. correlate protection for virus, a nonenteric pathogen, is blood serum antibody titers against HBsAg. After volunteers ate uncooked potatoes, anti-HBsAg increased 10 16 (62.5%) who three potatoes; 9...
The molecular orientation of regioregular poly(3-hexylthiophene) varies from edge-on to plane-on depending on the film drying rate controlled by spin-coating speed. field effect hole mobility accordingly. Orientation was determined with near-edge X-ray fine structure spectroscopy π* resonance, which is orthogonal conjugated plane.
We measured the molecular order of poly(3-alkylthiophene) chains in thin films before and after melting through combination several polarized photon spectroscopies: infrared (IR) absorption, variable angle spectroscopic ellipsometry (SE), near-edge X-ray absorption fine structure (NEXAFS). The data from various techniques can be uniformly treated context dielectric constant tensor ε for film. combined spectroscopies allow determination orientation distribution main-chain axis (SE IR),...