Photoluminescence in transition metal dichalcogenides: Towards high quantum yield

Owing to their atomic-level thickness, strong light-matter interaction, and wide range of bandgap tunability, transition metal dichalcogenides (TMDCs) hold great promise as light-emitting materials. Research on photoluminescence (PL) plays an indispensable role in the development of related fields, with efficiency being one of the most critical metrics for evaluating luminescence performance. Distinct from conventional direct-bandgap semiconductors, the unique exciton luminescence characteristics of TMDCs have established a new paradigm for investigating PL properties while simultaneously posing fresh challenges for modulating PL efficiency. Consequently, the study of PL efficiency modulation in TMDCs carries both fundamental physical significance and engineering application value. Based on an understanding of exciton physics in TMDCs, this review first summarizes strategies for enhancing PL quantum yield (QY) under low generation rates, including doping, defect engineering, interface engineering, and optical engineering. Subsequently, several strategies for suppressing exciton-exciton annihilation (EEA) under high generation rates are introduced. Finally, the current challenges are summarized, and an outlook on future development directions is provided.