Realization of interfacial defect-induced photocatalytic gating at the TiO2/ZnO interface

Abstract

We demonstrated and probed interface trap-induced photoelectrochemical sensitization by defect reactions at the TiO2/ZnO interface formed through atomic layer deposition of ZnO. The presence of interfacial defects at the TiO2/ZnO was confirmed through photoluminescence measurement in which green emission was observed. The photoelectrochemical photocurrent (PECP) increased due to interfacial defect-induced charge transfer from ZnO to TiO2 under illumination with a green light, while the PECP decreased under illumination with a solar simulator including UV compared to that without ZnO due to a reduced depletion layer width in the TiO2. We elaborated on the role of the TiO2/ZnO interfacial defects by depleting the total ZnO layer sandwiched by the TiO2/ZnO and the ZnO/electrolyte interfaces, through which the dark current is minimized, and the PECP by interfacial traps is maximized.