Optimizing the optoelectronic property of vapor-deposited CsPbCl3 films by triphenylphosphine oxide doping for high-performance self-powered UV detection

The emerging wide-bandgap CsPbCl₃ perovskite has drawn tremendous attention in ultraviolet (UV) detection application. Nevertheless, the massive internal and surface defects in CsPbCl₃ polycrystalline films are harmful for the detector performance and stability. Hence, an organic triphenylphosphine oxide (TPPO) doping strategy for passivating CsPbCl 3 defects is developed for the first time, in which the TPPO doping is completed by vapor technique. The P = O group in TPPO can form strong P = O-Pb dative bonds with the uncoordinated Pb 2 + ions in CsPbCl 3 perovskite by donating lone electron pair on O atoms, thus passivating the Cl vacancy defects existing in the evaporated CsPbCl₃ films. After TPPO doping, the crystallization process, film morphology, optical absorption ability and carrier lifetime are ameliorated, while the trap state density of the CsPbCl 3 film are pronouncedly alleviated. This conduces to a more efficient carrier extraction as well as declined charge recombination and noise current, further boosting the overall UV detection parameters. The optimized 12 nm TPPO-doped CsPbCl 3 photodetector obtains a detectivity of 7.68 × 10 12 Jones, a current on/off ratio of 5.08 × 10⁵, and a response time of 2.16 μs at 0 V bias. Furthermore, TPPO-doped device achieves superior stability under long-term continuous or intermittent UV irradiation in ambient environment. This work proposes an efficient approach for defect passivation of hardly soluble CsPbCl 3 perovskite, boosting its commercial development in UV detection field.