Evidence of Exciton Annihilation on Bimolecularly Recombining Charge Carriers in Two-Dimensional Monolayers

Abstract

In this work, we analyze the exciton annihilation on electrons and holes, which form the Langevin pairs before a bimolecular recombination. This physical mechanism has not been considered before for two-dimensional (2D) materials. Based on the kinetic model, which includes a newly derived the Langevin recombination coefficient for 2D structures, we are able to explain experimental results of the quantum yield of photoluminescence obtained for MoSe₂, WSe₂, MoS₂ and WS₂ monolayers. It proves that the interaction between excitons and charge carriers can play an important role in 2D monolayers.