High Performance BiOCl Nanosheets/TiO 2 Nanotube Arrays Heterojunction UV Photodetector: The Influences of Self‐Induced Inner Electric Fields in the BiOCl Nanosheets

Abstract BiOCl nanosheets/TiO 2 nanotube arrays heterojunction UV photodetector (PD) with high performance is fabricated by a facile anodization process and an impregnation method. The heterojunction at the interface and the internal electric fields in the BiOCl nanosheets faciliate the separation of photogenerated charge carriers and regulate the transportation of the electrons. Compared with the large dark current (≈10 −5 A), low on/off ratio (8.5), and slow decay time (>60 s) of the TiO 2 PD, the optimized heterojunction PD (6‐BiOCl–TiO 2 ) yields dramatically decreased dark current (≈1 nA), ultrahigh on/off ratio (up to 2.2 × 10 5 ), and fast decay speed (0.81 s) under 350 nm light illumination at −5 V. Moreover, it exhibits an increased responsivity of 41.94 A W −1 , a remarkable detectivity ( D *) of 1.41 × 10 14 Jones, and a high linear dynamic range of 103.59 dB. The loading amount and growth orientations of the BiOCl nanosheets alter the roles of the self‐induced internal electric field in regulating the behaviors of the charge carriers, thus affecting the photoelectric properties of the heterojunction PDs. These results demonstrate that rational construction of novel heterojunctions hold great potentials for fabricating photodetectors with high performance.