First-Principle Investigations of Carrier Multiplication in Si Nanocrystals: a Short Review

TL;DR

This paper reviews and discusses ab-initio investigations into carrier multiplication in silicon nanocrystals, focusing on a newly proposed space separated quantum cutting process and its role in multiexciton generation.

Contribution

It introduces ab-initio results on carrier multiplication effects in strongly interacting silicon nanocrystals and explores conditions for Auger unaffected multiexciton formation.

Findings

Identification of conditions for space separated quantum cutting

Simulation of multiexciton generation dynamics

Insights into non-radiative recombination mechanisms

Abstract

Carrier Multiplication (CM) is a Coulomb-driven non-radiative recombination mechanism which leads to the generation of multiple electron-hole pairs after absorption of a single high-energy photon. Recently a new CM process, termed space separated quantum cutting, was introduced to explain a set of new experiments conducted in dense arrays of silicon nanocrystals. The occurrence of this effect was hypothesized to generate the formation of Auger unaffected multiexciton configurations constituted by single electron-hole pairs distributed on different interacting naocrystals. In this work we discuss ab-initio results obtained by our group in the study of CM effects in systems of strongly interacting silicon nanocrystals. By solving a set of rate equations, we simulate the time evolution of the number of electron-hole pairs generated in dense arrays of silicon nanocrystals after absorption of high energy photons, by describing the circumstances under which CM dynamics can lead to the generation of Auger unaffected multiexciton configurations.