INVESTIGATING THE PHOTOPHYSICS OF WET-CHEMICALLY SYNTHESIZED COLLOIDAL SEMICONDUCTOR NANOCRYSTALS

Abstract

Due to their size- and composition dependent color tunability, high photostability and flexible surface chemistry, colloidal semiconductor nanocrystals (CSNs) display high potential as an alternative to organic dyes in the context of optical gain. This thesis summarizes our present understanding of the underlying optical properties of CSNs. Chapter 2 elaborates a novel alloyed CdSeS NCs which show composition dominated size-independent emission wavelength. Their tunable emission wavelength spans from blue to red in visible spectra and slow Auger process indicates their potential as gain media in laser device. Their corresponding low threshold amplified spontaneous emission behavior is investigated in Chapter 3. In Chapter 4, a dispersion of colloidal CdSe/CdS nanoplatelets capable of exhibiting ultralow threshold multiphoton pumped biexcitonic lasing within a cuvette-based Fabry-Perot optical resonator is developed. Chapter 5 discusses in details about the delayed exciton formation occurring within a newly developed CSN group, all-inorganic CsPbBr3 perovskite.