Synergistic Effects of Plasmonic Au Nanoislands on a MoSe₂ Nanoflake/ZnO Nanorod Heterostructure for an Enhanced Broadband Photoresponse

We report the enhanced photodetection properties of MoSe2/Au–ZnO vertical heterostructures by probing the synergistic effect of Au nanoislands on the optical response of one-dimensional (1D) vertically standing ZnO nanorods (NRs) and few-layer two-dimensional (2D) MoSe2 nanoflakes, collectively. Plasmonic effects mediated strong light–matter interactions in Au–ZnO hybrids are established through spectroscopic studies. A notable red shift accompanied by a quenched intensity of visible photoluminescence of ZnO NRs supports the energy transfer process from ZnO NRs to Au nanoislands in the plasmonic hybrid. The coupling of defect-originated green emission of ZnO NRs with plasmonic absorption (∼560 nm) and the strategic position of Au nanoislands facilitate easy transfer of plasmonic charge carriers across the heterojunctions and enhance the signal throughout the total operational bandwidth (up to ∼900 nm) of the devices considerably. Such robust devices using 2D/1D mixed-dimensional heterostructures and their direct resonant coupling with strategically integrated 0D plasmonic nanoislands make highly responsive (∼0.43 A/W) broadband photodetectors for future nanophotonic applications.