Improving Charge Transfer under Strong Coupling Conditions via Interfacial Modulation

Plasmon-induced carrier transfer at metal/semiconductor Schottky junctions is a novel approach for photo energy conversion. Here, we propose a strategy for improving electron transfer at the Au/TiO2 heterojunction by modifying the Au/TiO2 structures under modal strong coupling conditions to demonstrate the efficacy of our proposal. Via transient absorption measurements, we found that the apparent quantum efficiency (AQE) of electron injection into TiO2 increased by ∼1.8-fold as the thickness of the Ti layer increased from 0.5 to 5.0 nm under the modal strong coupling conditions. This AQE enhancement was attributed to the energy transfer from AuNDs to the Ti layer through the near-field, resulting in a production of high-energy electrons in the Ti layer to inject into the conduction band of TiO2, thereby improving the electron transfer efficiency. Our observations offer valuable insight into the future design of plasmonic devices aimed at efficiently utilizing plasmon-induced hot carriers.