A Pressure-Induced Emergence of a Weyl Semimetal Phase in Pb1-xSnxTe

Outcome: In collaboration with experimental studies at Princeton University we have carried out ab initio calculations to examine the effect of pressure on the topological phase diagram of Pb1-xSnxTe. The calculations reveal that the ferroelectric polarization, which breaks crystal inversi

Charge Stripe Formation in Molecular Ferroelectric Organohalide Perovskites for Efficient Charge Separation

Despite rapid progress in the efficiency of organohalide perovskite based solar cells, physical mechanisms underlying their efficient charge separation and slow charge recombination still elude us. In this work, we provide first direct evidence of spontaneous charge separation via first-pr

Polymer/Carbon Spheres Composites for Device Applications

Intellectual Merit: Carbon-based materials have attracted scientific interest due to their promise to revolutionize the electronics industry. Carbon Spheres (CS) were produced via hydrothermal carbonization of sucrose. A Schottky diode was fabricated using a composite of the highly conduct

A Pressure-Induced Emergence of a Weyl Semimetal Phase in Pb1-xSnxTe

Outcome: In collaboration with experimental studies at Princeton University we have carried out ab initio calculations to examine the effect of pressure on the topological phase diagram of Pb1-xSnxTe. The calculations reveal that the ferroelectric polarization, which breaks crystal inversi

One-Step Synthesis of Fluorescent Graphene Quantum Dots Through Pyrolysis of Amino Acids

Outcome: We have developed a novel method for the synthesis of graphene quantum dots (GQDs) by using two amino acids, which are non-toxic natural materials containing nitrogen groups for easy surface modification. The synthesis process was easy, efficient and no toxic chemicals were involv

New Fullerene Derivatives for Electron Transporting Materials in Inverted Planar Perovskite Solar Cells

Perovskite solar cells (PSCs), have shown a remarkable increase in photoconversion efficiency (PCE), from 3.8%  in 2009, to 22.1% in 2016. The good electron transporting and solution processable properties of most fullerene derivatives make them the most popular electron transporting mater

Integrated 3D printing with in-situ functionalization of piezoelectric nanocomposites

Our research supported by the NSF PREM project studied the synthesis, fabrication, and characterization of advanced materials for sensing, energy harvesting, and storage. Our integrated 3D printing with in-situ functionalization of piezoelectric nanocomposite enabled us design nanocomposit

Development of chemical and biological sensors: Synthesis of Plasmonic Nanoparticles and Multispectral Imaging Nanostructures

How? Synthesizing and isolation of ultra-small gold nanoparticles with a specific shape or structure. We have developed a facile approach for shape-controlled synthesis of gold nanoparticles using KBr and 5-hydroxyindoleacetic acid (5-HIAA) as the reducing agent. 

What happens to photogenerated charges in semiconductor nanowires?

How? We use optical microscopy to determine the dynamics of photo-generated charges in individual semiconductor nanowire hetero-structures.

Investigation of Indium Free Transparent Conducting Oxides for Application in Photovoltaics

Transparent conducting oxide play a key role in photovoltaic (PV) devices. There has been much recent interest in finding alternative indium (In) free TCOs and even better performing alternative candidates to substitute for standard ITO.  The driving factors are: scarcity, unintended inter

Synthesis of Fullerene Derivatives for Potential Applications in OPV Devices

We have separated Sc3N@D5h-C80 from Sc3N@C68 based on their chemical reactivity differences using the p-toluenesulfonyl tosyl hydrazone of phenyl butyric acid methyl ester (PCBM). We also performed for the first time the synthesis and characterization of five PCBM methano

Ultraviolet Tunable MoS2/p-Silicon Junction Diode

MoS2 single crystals were transferred onto the edge of a p-Si/SiO2 wafer, forming an abrupt heterogeneous junction diode at the MoS2/p-Si interface. When electrically characterized as a field effect transistor, MoS2 exhibits an n-type response and can be doped in the presence of ultraviole