Enhanced UV Photoresponse Performances of TiO₂/Bi₂Se₃ Heterostructure‐Based Photoelectrochemical Photodetector

Bi 2 Se 3 has a unique surface state and excellent electron transport performance, but because of its narrow band gap, Bi 2 Se 3 ‐based photodetectors are difficult to achieve high response to ultraviolet (UV) light. In this paper, the TiO 2 /Bi 2 Se 3 heterostructure was constructed by spin‐coating TiO 2 on Bi 2 Se 3 film, and TiO 2 /Bi 2 Se 3 heterostructure‐based photoelectrochemical (PEC) photodetector was constructed, and a series of measurements were carried out. The measure results showed that the photoresponse performance of TiO 2 /Bi 2 Se 3 heterostructure‐based photodetector was improved in the visible region, and the performance in the UV was further improved. This is because the type ii band alignment between TiO 2 and Bi 2 Se 3 is beneficial for the effective separation and transfer of photogenerated electron‐hole pairs, reducing recombination losses and enhancing the overall photoresponse. In addition, under the action of the built‐in electric field formed by the heterostructure, the photogenerated electrons and holes are easier to separate, which reduces the recombination probability of the photogenerated electron‐hole pair and improves the photoelectric conversion efficiency. In the UV, TiO 2 /Bi 2 Se 3 heterostructure can make more efficient use of the light absorption characteristics of TiO 2 and absorb more photons, resulting in a larger photocurrent. These results indicate that TiO 2 /Bi 2 Se 3 heterostructure‐based photodetector has great application potential in the UV.