Defect-induced anomalous thermal quenching of photoluminescence in the transition metal dichalcogenide ternary alloy Mo0.6W0.4S<mml:mi mathvariant="…

We report negative thermal quenching of photoluminescence (PL) in few-layered Mo0.6W0.4Se₂ flakes. A comparative study of temperature-dependent PL from two groups of Mo0.6W0.4Se₂ flakes, one with defects and the other with negligible defects, shows that this anomalous enhancement in the PL with increasing temperature is due to the dissociation of defect-bound excitons at higher temperatures. The relaxation dynamics of the carriers localized at these defect states were studied using the ultrafast pump-probe technique, which shows that the photogenerated carriers are trapped at these defects on a timescale of ≈3 ps.