Defect passivation induced strong photoluminescence enhancement of rhombic monolayer MoS₂

Growing high quality monolayer MoS₂ with strong photoluminescence (PL) is essential to produce light-emitting devices on the atomic scale. In this study we show that rhombic monolayer MoS₂ with PL intensity 8 times stronger than those of chemical vapour deposition (CVD)-grown triangular and mechanically exfoliated (ME) monolayer MoS₂ can be prepared by using CVD. Both Raman and PL measurements indicate low density of defects in rhombic monolayer MoS₂ with enhanced PL intensity. Density functional theory (DFT) calculations show that passivation of defects in MoS₂ removes trapping gap states, which may finally result in PL enhancement.