A5087423395- Thermal properties of materials
- Advanced Thermoelectric Materials and Devices
- Machine Learning in Materials Science
- Perovskite Materials and Applications
- Quantum Dots Synthesis And Properties
- Chalcogenide Semiconductor Thin Films
- Graphene research and applications
- Thermal Radiation and Cooling Technologies
- Electrocatalysts for Energy Conversion
- 2D Materials and Applications
- Solid-state spectroscopy and crystallography
- High-pressure geophysics and materials
- Ferroelectric and Negative Capacitance Devices
- Thermography and Photoacoustic Techniques
- Natural product bioactivities and synthesis
- Gold and Silver Nanoparticles Synthesis and Applications
- Phytochemistry and Bioactive Compounds
- Smart Materials for Construction
- Nuclear Materials and Properties
- Conducting polymers and applications
- Carbon Nanotubes in Composites
- Organic Light-Emitting Diodes Research
- Thermodynamic and Structural Properties of Metals and Alloys
- Advanced battery technologies research
- Heat Transfer and Optimization
Indian Institute of Technology Bombay
2020-2025
Stanford University
2018-2020
Interface (United States)
2020
SLAC National Accelerator Laboratory
2020
University of Toronto
2016-2019
Carnegie Mellon University
2012-2019
IPS Academy
2012-2019
Technical University of Denmark
2019
Planar perovskite solar cells (PSCs) made entirely via solution processing at low temperatures (<150°C) offer promise for simple manufacturing, compatibility with flexible substrates, and perovskite-based tandem devices. However, these PSCs require an electron-selective layer that performs well similar processing. We report a contact-passivation strategy using chlorine-capped TiO2 colloidal nanocrystal film mitigates interfacial recombination improves interface binding in low-temperature...
Abstract Using first principles calculations, we predict the thermal conductivity of two-dimensional materials black phosphorene and blue phosphorene. Black has an unprecedented anisotropy ratio three, with predicted values 110 W/m-K 36 along its armchair zigzag directions at a temperature 300 K. For phosphorene, which is isotropic structure, value 78 W/m-K. The two allotropes show strikingly different accumulation, phonons mean free paths between 10 nm 1 μm dominating in while much narrower...
Perovskite nanocrystals (NCs) have attracted attention due to their high photoluminescence quantum yield (PLQY) in solution; however, maintaining emission efficiency the solid state remains a challenge. This study presents solution‐phase synthesis of efficient green‐emitting perovskite NCs (CsPbBr 3 ) embedded robust and air‐stable rhombic prism hexabromide (Cs 4 PbBr 6 microcrystals, reaching PLQY 90%. Theoretical modeling experimental characterization suggest that lattice matching between...
Abstract Bismuth‐based hybrid perovskites are candidates for lead‐free and air‐stable photovoltaics, but poor surface morphologies a high band‐gap energy have previously limited these perovskites. A new materials processing strategy to produce enhanced bismuth‐based thin‐film photovoltaic absorbers by incorporation of monovalent silver cations into iodobismuthates is presented. Solution‐processed AgBi 2 I 7 thin films prepared spin‐coating bismuth precursors dissolved in n‐butylamine...
Mode-dependent phonon and electron transport properties in Al, Ag, Au are predicted using density functional theory lattice dynamics calculations. The thermal conductivities, electrical electron-phonon coupling coefficients, mass enhancement parameters agreement with experimental measurements. At a temperature of 100 K, the contribution to total conductivity Al is 5% bulk increases 15% for 50 nm thick film. In all three metals, phonons mean free paths between 1 10 dominate contributors at...
A computational framework for predicting phonon frequencies, group velocities, scattering rates, and the resulting lattice thermal conductivity is described. The underlying theory implementation suggestions are also provided. By using input from first principles calculations taking advantage of advances in power, this has enabled predictions that agree with experimental measurements diverse crystalline materials over a wide range temperatures. Density functional density perturbation used to...
Colloidal quantum dots (CQDs) allow broad tuning of the bandgap across visible and near-infrared spectral regions. Recent advances in applying CQDs light sensing, photovoltaics, emission have heightened interest achieving further synthetic improvements. In particular, improving monodispersity remains a key priority order to improve solar cells' open-circuit voltage, decrease lasing thresholds, photodetectors' noise-equivalent power. Here we utilize machine-learning-in-the-loop learn from...
We use high-throughput density functional theory calculations to screen lead-free perovskite-like materials with compositions A2BB′X6, ABX4, and A3B2X9 for optoelectronic performance. monovalent A B′ cations from Na, K, Rb, Cs Cu, Ag, trivalent B Ga, In, Sb, anions Cl, Br, I. Our screening procedure is based on formation energy hybrid HSE06 predicted bandgaps. screened more than 480 compounds found 10 that have bandgaps in the 1.5–2.5 eV range. Of these compounds, seven are new, not having...
The thermal conductivities of solid silicon thin films and with periodic pore arrays are predicted using a Monte Carlo technique to include phonon-boundary scattering the Boltzmann transport equation. bulk phonon properties required as input obtained from harmonic anharmonic lattice dynamics calculations. force constants for calculations forces calculated density functional theory. For both porous films, in-plane conductivity predictions capture magnitudes trends previous experimental...
The strain-dependent phonon properties and thermal conductivities of a soft system [Lennard-Jones (LJ) argon] stiff (silicon modeled using first-principles calculations) are predicted lattice dynamics calculations the Boltzmann transport equation. As is commonly assumed for materials under isotropic strain, conductivity LJ argon decreases monotonically as moves from compression into tension. reduction in attributed to both lifetimes group velocities. silicon, however, constant only begins...
The discovery of high-performing and stable materials for sustainable energy applications is a pressing goal in catalysis science. Understanding the relationship between material's structure functionality an important step process, such that viable polymorphs given chemical composition need to be identified. Machine-learning-based surrogate models have potential accelerate search target specific applications. Herein, we report readily generalizable active-learning (AL) accelerated algorithm...
We report the phonon thermal transport properties of two-dimensional (2D) and bulk boron chalcogenides using density functional theory-driven Boltzmann equation approach by considering three- four-phonon scatterings. The calculated conductivities for 2D sulphide (BS), selenide (BSe), telluride (BTe) at 300 K are 210, 57, 125 W/m vary non-monotonically with chalcogen mass. effect scattering is significant in all materials obtained overpredicted as much 83% when only three-phonon included. For...
We propose a method by which the thermal conductivity of nanostructure with arbitrary geometry can be predicted through Monte Carlo sampling free paths associated phonon-phonon and phonon-boundary scattering. The required inputs are bulk phonon frequencies, group velocities, mean paths. is applied to thin film in in-plane cross-plane directions polycrystalline material. For film, faster approach found compared predictions made using Matthiessen rule path an average scattering length.
Using density functional theory-predicted energies, we performed a high-throughput screening of more than 11 000 two-dimensional materials from available material databases. We suggest that less 35 are stable under the strongly oxidizing operating conditions oxygen reduction and/or evolution reactions in acidic media.
The validity of the particlelike phonon picture in describing thermal transport physics strongly anharmonic crystalline materials is a subject recent debate. On one hand, Peierls-Boltzmann equation-based treatment phonons was found to be insufficient explaining experimentally observed ultralow conductivity ${\text{Tl}}_{3}\text{V}{\text{Se}}_{4}$, and subsequently another theory based on an additional channel proposed. other this multichannel questioned through higher-level accounting for...
We design quasi-type-II CdSe/CdS core–shell colloidal quantum dots (CQDs) exhibiting a suppressed Auger recombination rate. do so using fully atomistic tight-binding wave functions and microscopic Coulomb interactions. The rate as function of the core shell size shape is tested against experiments. Because higher density deep hole states stronger confinement, found to be up six times faster for positive trions compared negative ones in 4 nm core/10 CQDs. Soft-confinement at interface results...
The high-throughput screening of periodic inorganic solids using machine learning methods requires atomic positions to encode structural and compositional details into appropriate material descriptors. These are not available {\it a priori} for new materials which severely limits exploration novel materials. We overcome this limitation by only crystallographic symmetry information in the description show that with identical symmetry, is trivial accuracies similar density functional theory...
The thermal transport properties of single-wall carbon nanotubes (SWCNTs) are reinvestigated using the iterative solution Boltzmann equation by including four-phonon scattering. Using only three-phonon scattering, flexural and twisted phonon modes found to remain nonscattered via Umklapp processes. However, with while longitudinal unaffected, transverse undergo predicted conductivity SWCNTs both three- scatterings is 4000 W/m-K at 300 K, stays highest amongst all known materials.
Abstract Bismuth‐based hybrid perovskites are candidates for lead‐free and air‐stable photovoltaics, but poor surface morphologies a high band‐gap energy have previously limited these perovskites. A new materials processing strategy to produce enhanced bismuth‐based thin‐film photovoltaic absorbers by incorporation of monovalent silver cations into iodobismuthates is presented. Solution‐processed AgBi 2 I 7 thin films prepared spin‐coating bismuth precursors dissolved in n‐butylamine...