Near-Ultraviolet Light-Driven Photocathodic Activity for (001)-Oriented BiOCl Thin Films Synthesized by Mist Chemical Vapor Deposition

Semitransparent and homogeneous bismuth oxychloride (BiOCl) thin films with (001) preferred orientation were synthesized on polycrystalline Sn:In₂O₃-glass substrates by mist chemical vapor deposition. The films showed photocathodic activity even under near-ultraviolet light within the band gap due to the in-gap states induced by oxygen vacancies. Higher synthesis temperatures resulted in a significant increase of photocurrent density under ultraviolet light. While the longer lifetime of photocarriers led to an increase of internal quantum efficiency, the larger band-edge absorption significantly contributed to the higher external quantum efficiency.