Quasiparticle Electronic Structure and Optical Properties of CdS Quantum Dots and their Assemblies in Different Dimensions

Quantum dots have received considerable attention due to the exceptional optoelectronic properties which stem from their confinement. Covalently linking these quantum dots forms gel-like assemblies, whose properties differ from the isolated quantum dots. The understanding of the electronic structure of these materials at the atomistic level is crucial for optimizing their performances in devices. Prior computational investigations on the structure-property relationship have been limited to empirical, tight-binding models, and local/semi-local density functional studies on very small quantum dots. The fundamental differences in the electronic structure and optical properties between quantum dot assemblies and isolated quantum dots are largely unknown. In this work, we employ the first-principles GW-BSE approach to study the structural-property relationships of CdS quantum dots and their assemblies in various dimensions (i.e., 0D, 1D, 2D, and 3D). Our results are in quantitative agreement with experiments and unveil the effect of dimensionality on the modulation of the quantum dot properties.