Near-unity photoluminescence quantum yield in MoS ₂

Brighter molybdenum layers The confined layers of molybdenum disulphide (MoS 2 ) 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 MoS 2 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. 1065