Highly Efficient Exciton Modulation in MoSe₂/PdSe₂ Heterostructures

We report a pronounced ∼6-fold enhancement of room-temperature A-exciton emission in a type-I MoSe2/PdSe2 van der Waals heterostructure, yielding a photoluminescence quantum yield of 6%, as compared to ∼1% for as-exfoliated monolayer MoSe2. This unusual enhancement is accompanied by strong quenching of the B exciton, consistent with interlayer electronic coupling that redistributes exciton populations toward the radiative A-exciton channel. Power- and temperature-dependent measurements reveal a suppression of exciton–exciton annihilation and a crossover to quenched emission at a low temperature, indicating a redistribution of exciton relaxation pathways. Photoluminescence excitation spectroscopy further reveals a broadband enhancement spanning 450–725 nm. These results demonstrate that interlayer electronic coupling can be used as an efficient means to redirect exciton populations toward radiative channels, enhancing emission efficiency in two-dimensional semiconductors without chemical modification or significant strain.