Research

Hot Carrier Dynamics in Two-Dimensional Perovskites

Dr. Ghosh’s group investigates how photoexcited charge carriers—often referred to as hot carriers—behave immediately after light absorption in two-dimensional lead halide perovskites. Their research focuses on understanding how these energetic carriers lose excess energy through cooling processes and how the crystal structure, dimensional confinement, and organic spacer layers influence these relaxation pathways. By employing time-resolved optical spectroscopy, the group captures ultrafast carrier cooling events, providing insight into the role of structural distortions and interlayer coupling. This understanding is critical for designing perovskite materials capable of slowing down carrier cooling, thereby enhancing their potential for high-efficiency solar energy conversion and hot-carrier optoelectronics.

Electron–Phonon Coupling and Lattice Dynamics

A major focus of Dr. Ghosh’s work lies in elucidating electron–phonon interactions—how charge carriers interact with the lattice vibrations that make up the material’s atomic framework. His recent publications highlight how vibrational modes in Ruddlesden–Popper type 2D perovskites influence carrier relaxation, recombination, and photoluminescence properties. By tracking changes in transient absorption spectra, his group quantifies the strength and timescales of these couplings, revealing how structural rigidity or softness affects material performance. This research offers fundamental insight into the balance between structural dynamics and charge transport efficiency, a key determinant for stable and high-performance perovskite devices.

Photophysics of Semiconductor Nanocrystals

Beyond perovskites, Dr. Ghosh’s group also explores the photophysical behavior of semiconductor nanocrystals such as PbS quantum dots. His work examines how excitons—bound electron-hole pairs—form, interact, and decay within these confined systems. Recent studies delve into spectator exciton effects, revealing how non-participating excitons influence optical gain and emission. By tailoring crystal size, surface passivation, and dimensionality, the group seeks to tune the optical and electronic properties of nanocrystals for quantum dot photovoltaics, light emission, and optoelectronic sensing applications.