Polaron States as a Massive Electron-Transfer Pathway at Heterojunction Interface

For heterojunction semiconductor photoelectrodes, efficient charge separation is localized in the junction-induced electric field region and charge transfer follows a band-to-band charge-transfer pathway. Here, we found that polaron states at the heterojunction interface have a function of storing and transferring electrons. As a successful demonstration, we verified that the polaron states (Ti³⁺OH) on TiO₂ are not passivated when used to create a CdS/TiO₂ heterojunction and function as an efficient pathway for massively capturing, storing, and transferring the electrons from conduction bands of both TiO₂ and CdS, thus effectively enhancing the charge separation efficiency of the heterojunction photoanode. The electron throughput of polaron states remains a positive correlation with polaron state density. Interfacial electron transfer through the TiO₂ surface polaron states has great potential application in the development of high-performance heterojunction devices based on TiO₂.