Special Condensed Matter Physics Seminar
Speaker: Sachin Dev Verma, University of Cambridge
Title: Hot-carrier cooling in hybrid Pb-Sn halide perovskites
Date: Tue, 03 Jul 2018, 2:00 pm – 3:00 pm
Location: 1400 BPS Bldg.
Organic-inorganic hybrid perovskites have emerged as an excellent class of semiconductors owing to their exceptional optoelectronic properties. Enormous efforts are being made globally to understand their photophysical properties to improve their design and utilization in solar cells, light emitting diodes, photo-detectors, and lasers. However, a deep understanding about hot-carrier dynamics, responsible for thermalization losses in solar cells, in these class of semiconductors remain modest. Excitation of charges from valence band (VB) to higher energies in conduction band (CB) generates hot-carriers, i.e. electrons (holes), in a Boltzmann distribution with kinetic energies above CB. Underlying mechanism of hot-carrier cooling is of fundamental importance for enhancing the device performance. In this talk, I will take you on a tour of transient absorption spectroscopy (TAS) and microscopy (TAM) which employ ~10 fs pulses. I will show you how hot-carrier cooling dynamics can be observed from TAS, and how we can tune it to make perovskites a potential candidate for efficient solar cells. Brief overview will also be provided on how state-of-the-art TAM can enable us to directly monitor carrier transport in photo-voltaic materials.