PT  - JOURNAL ARTICLE
AU  - Amani, Matin
AU  - Lien, Der-Hsien
AU  - Kiriya, Daisuke
AU  - Xiao, Jun
AU  - Azcatl, Angelica
AU  - Noh, Jiyoung
AU  - Madhvapathy, Surabhi R.
AU  - Addou, Rafik
AU  - KC, Santosh
AU  - Dubey, Madan
AU  - Cho, Kyeongjae
AU  - Wallace, Robert M.
AU  - Lee, Si-Chen
AU  - He, Jr-Hau
AU  - Ager, Joel W.
AU  - Zhang, Xiang
AU  - Yablonovitch, Eli
AU  - Javey, Ali
TI  - Near-unity photoluminescence quantum yield in MoS<sub>2</sub>
AID  - 10.1126/science.aad2114
DP  - 2015 Nov 27
TA  - Science
PG  - 1065--1068
VI  - 350
IP  - 6264
4099  - http://science.sciencemag.org/content/350/6264/1065.short
4100  - http://science.sciencemag.org/content/350/6264/1065.full
SO  - Science2015 Nov 27; 350
AB  - The confined layers of molybdenum disulphide (MoS2) exhibit photoluminescence that is attractive for optolectronic applications. In practice, efficiencies are low, presumably because defects trap excitons before they can recombine and radiate light. Amani et al. show that treatment of monolayer MoS2 with a nonoxidizing organic superacid, bis(trifluoromethane) sulfonimide, increased luminescence efficiency in excess of 95%. The enhancement mechanism may be related to the shielding of defects, such as sulfur vacancies.Science, this issue p. 1065Two-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.