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.
@article{arxiv.1905.03365,
title = {Electrical suppression of all nonradiative recombination pathways in monolayer semiconductors},
author = {Der-Hsien Lien and Shiekh Zia Uddin and Matthew Yeh and Matin Amani and Hyungjin Kim and Joel W. Ager and Eli Yablonovitch and Ali Javey},
journal= {arXiv preprint arXiv:1905.03365},
year = {2019}
}