Near-unity photoluminescence quantum yield in MoS ₂

TLDR

Two-dimensional transition metal dichalcogenides, especially MoS₂, exhibit extremely low room‑temperature photoluminescence quantum yields (≤0.6 %) due to high defect densities. The study aims to develop an air‑stable, solution‑based superacid treatment that dramatically boosts MoS₂ monolayer photoluminescence and carrier lifetime. The authors apply an organic superacid to MoS₂ monolayers, uniformly enhancing photoluminescence and minority carrier lifetime by over two orders of magnitude. The treatment suppresses defect‑mediated nonradiative recombination, achieving a quantum yield above 95 % and a lifetime of 10.8 ± 0.6 ns, enabling highly efficient 2D optoelectronic devices.

Abstract

Two-dimensional (2D) transition metal dichalcogenides have emerged as a promising material system for optoelectronic applications, but their primary figure of merit, the room-temperature photoluminescence quantum yield (QY), is extremely low. The prototypical 2D material molybdenum disulfide (MoS2) is reported to have a maximum QY of 0.6%, which indicates a considerable defect density. Here we report on an air-stable, solution-based chemical treatment by an organic superacid, which uniformly enhances the photoluminescence and minority carrier lifetime of MoS2 monolayers by more than two orders of magnitude. The treatment eliminates defect-mediated nonradiative recombination, thus resulting in a final QY of more than 95%, with a longest-observed lifetime of 10.8 ± 0.6 nanoseconds. Our ability to obtain optoelectronic monolayers with near-perfect properties opens the door for the development of highly efficient light-emitting diodes, lasers, and solar cells based on 2D materials.