Research

Thermally Activated Single-Photon Up-Conversion

CsPbBr3 perovskite nanocrystals will emit high energy light from the band edge when excited with low energy sub-gap light, in a processes known as anti-Stokes photoluminescence (ASPL). This unique form of optical up-conversion is a single photon processes, where one low energy photon is absorbed and one high energy photon is emitted, the increase in energy coming from the thermal energy of the nanocrystals. When it occurs in a material with near unity photoluminescent quantum yield (PLQY) the temperature of the system decreases as thermally energy is removed during up-conversion in a processes called optical cooling. We study the mechanism of ASPL is CsPbBr3 nanocrystals in order to better better understand how optical cooling occurs in these materials and how to optimize their use for optical cooling applications.

Investigation of the Plasmoelectric Effect for power conversion devices​

We are investigating a new optical-to-electrical power conversion device strategy based on the recently discovered plasmoelectric (PE) effect in relation to the traditional thermoelectric effect. By creating a structural interface on the metal nanostructure, an electric current will flow upon optical excitation at the interface region.​

Electron-Phonon Interactions in CsPbBr3 Nanorods​

Using a slow injection technique, 1-D CsPbBr3 nanorods can be synthesized with crystal phase tunability. We seek to understand the effects of crystal phase on polaron formation, observable in the component analysis of the PL spectra, which show contributions from lower energy trap states.​

Perovskite Equilibrium Solution

Perovskite nanocrystals (PNCs) are a class of colloidal semiconductor that show exceptional promise for their use in various optoelectronic applications. Post-synthetic cleaning procedures use abrasive polar solvents which contribute to stripping of stabilizing ligands, leading to vacancies resulting in degradation of their desirable electronic properties. We propose the development of a solvent system that capitalizes on this chemical equilibrium for electronic surface passivation, stabilizing the PNC surface while being immune to dilution effects.

Light Rectification via Dipole Emitting Nanorods

Within the realm of Photovoltaic (PV) device manufacturing, Luminescent Solar Concentrators (LSCs) offer unique benefits as an economical replacement for expensive lens-based optical concentrators, while avoiding the need for solar tracking. Despite these benefits, traditional LSCs are unable to provide conversion efficiency improvements beyond the maximum theoretical limit of a single junction flat plate PV solar cell, at 33.7%. By modifying the angular distribution of radiative emission within the LSC, conversion efficiencies can exceed this limit. Our research examines the benefits achieved by embedding aligned nanorods, characterized by their anisotropic emission, within a LSC medium. Our model makes use of a Markov Chain approach, which allows for an computationally efficient means of modeling the macroscopic optical response of our system.

Boosting Resonant Interaction via Vibrational Strong Coupling

When dipole coupling between a molecular ensemble and the electromagnetic mode of a cavity allows for energy exchange that outcompetes all other decay pathways, the two systems hybridize to form light-matter quasiparticles called polaritons. The spectral signature of vibrational strong coupling (VSC) is the splitting of a molecular vibrational peak into upper and lower polariton states (UP and LP, respectively), separated in energy by the vacuum Rabi energy. There has recently been intense investigation into the possibility of controlling chemical processes of molecules placed inside optical cavities. We design and fabricate plasmonic nanocavities to enhance light-matter interaction in both near-field and far-field in order to understand mechanisms of chemical modification across various coupling regime.