Spectroscopic Investigation of Ultrafast Photo physical Processes in Chalcogenide Based Two Dimensional Material

Abstract

Since the discovery of monolayer graphene in 2004, there have been growing interest on two newlinedimensional (2D) layered materials, motivated by their outstanding optical, electrical, and newlinemechanical properties. These materials are blessed with many unique characteristics like, high newlinecharge carrier mobility, large surface area, strong light-matter interactions, tunable electronic band newlinestructure, large quasiparticle binding energy etc. The evolution of these layered entities has newlinerevolutionized the condensed matter opto-electronic field, owing to their potential in many newlineexquisite applications like lasers, light emitting diodes (LED), photodetectors, displays, optical newlinesensors, as well as in energy harvesting devices. The efficiencies of these optical devices would newlinebe primarily dependent on the material itself. Following the absorption of an electromagnetic newlineradiation, the material gets excited and follow many radiative and non-radiative pathways to relax newlineback to the ground state. So, in order to utilize the material better in an optical device, we need to newlinestudy those excited state photophysical processes inside the material. These processes are ultrafast newlinein nature and to monitor them we need a technique which can probe very short time scale processes. newlineTransient absorption spectroscopy (TAS) is one such technique; it can study ultrashort processes newlineoccurring in picosecond (ps), femtosecond (fs) or even attosecond (as) time scales. In my thesis newlinework, we have employed Femtosecond Transient Absorption Spectroscopy (FTAS) to study the newlineexcited state charge carrier dynamics in different 2D metal chalcogenides and their doped or newlineheterostructured counterparts.