Interface engineering of Ta3N5 thin film photoanode for highly efficient photoelectrochemical water splitting

Interface engineering is a proven strategy to improve the efficiency of thin film semiconductor based solar energy conversion devices. Ta3N5 thin film photoanode is a promising candidate for photoelectrochemical (PEC) water splitting. Yet, a concerted effort to engineer both the bottom and top interfaces of Ta3N5 thin film photoanode is still lacking. Here, we employ n-type In:GaN and p-type Mg:GaN to modify the bottom and top interfaces of Ta3N5 thin film photoanode, respectively. The obtained In:GaN/Ta3N5/Mg:GaN heterojunction photoanode shows enhanced bulk carrier separation capability and better injection efficiency at photoanode/electrolyte interface, which lead to a record-high applied bias photon-to-current efficiency of 3.46% for Ta3N5-based photoanode. Furthermore, the roles of the In:GaN and Mg:GaN layers are distinguished through mechanistic studies. While the In:GaN layer contributes mainly to the enhanced bulk charge separation efficiency, the Mg:GaN layer improves the surface charge inject efficiency. This work demonstrates the crucial role of proper interface engineering for thin film-based photoanode in achieving efficient PEC water splitting. Solar-to-fuel energy conversion requires well-designed materials properties to ensure favorable charge carrier movement. Here, authors employ interface engineering of Ta3N5 thin film to enhance bulk carrier separation and interface carrier injection to improve the water-splitting efficiency.

Automated summary

Interface engineering is an effective strategy to improve the efficiency of thin film semiconductor based solar energy conversion devices. In this study, n-type In:GaN and p-type Mg:GaN were employed to modify the bottom and top interfaces of Ta3N5 thin film photoanode, resulting in significant enhancements in efficiency.