Electrical suppression of all nonradiative recombination pathways in monolayer semiconductors

TL;DR

This paper demonstrates that electrostatic doping can nearly eliminate nonradiative recombination in monolayer TMDCs like MoS2 and WS2, achieving near-unity photoluminescence quantum yield without chemical passivation, thus easing defect density constraints.

Contribution

It reveals that intrinsic electrostatic doping can suppress nonradiative pathways in TMDC monolayers, enabling high PL efficiency without defect passivation.

Findings

PL QY reaches near-unity with electrostatic doping

Neutral exciton recombination is fully radiative despite defects

Eases defect density requirements for optoelectronic applications

Abstract

Defects in conventional semiconductors substantially lower the photoluminescence (PL) quantum yield (QY), a key metric of optoelectronic performance that directly dictates the maximum device efficiency. Two-dimensional (2D) transition metal dichalcogenides (TMDCs), such as monolayer MoS2, often exhibit low PL QY for as-processed samples, which has typically been attributed to a large native defect density. We show that the PL QY of as-processed MoS2 and WS2 monolayers reaches near-unity when they are made intrinsic by electrostatic doping, without any chemical passivation. Surprisingly, neutral exciton recombination is entirely radiative even in the presence of a high native defect density. This finding enables TMDC monolayers for optoelectronic device applications as the stringent requirement of low defect density is eased.