Surface Engineering and Nb₂CT_x‐Modulated CsPbCl₃ Perovskite for Self‐Powered UV Photodetectors with Ultrahigh Responsivity

Abstract All‐inorganic CsPbCl₃ perovskite has emerged as a promising material for ultraviolet (UV) photodetection, attributed to its appropriate bandgap and exceptional optoelectronic properties. However, the suboptimal film‐forming quality of the solution process, as well as the instability of films induced by UV radiation and the annealing process, have limited its popularization and application. Herein, the buried layer is pretreated with N, N‐dimethylacetamide (DMF) to improve surface hydrophilicity and facilitate the anchoring of Pb²⁺. Additionally, Nb₂CT_x is incorporated into the PbCl₂ precursor solution to enhance the quality of CsPbCl₃ films. Following surface engineering and Nb₂CT_x modification (CsPbCl₃@Nb₂CT_x), the morphology and optoelectronic properties of CsPbCl₃ films are optimized. Furthermore, the effect of lattice strain and defect state‐induced interface state on the nonradiative charge recombination is mitigated. Ultimately, the UV photodetector fabricated on fluorine‐doped tin oxide (FTO)/SnO₂/CsPbCl₃@Nb₂CT_x/Au architecture exhibits outstanding performance including remarkably high responsivity (up to 990 mA W⁻¹), significant specific detectivity (1.03 × 10¹¹ cm Hz^1/2 W⁻¹), and rapid rise/decay time (0.24/0.32 µs) under self‐powered mode, with markedly improved stability as well. This approach presents a novel strategy for optimizing CsPbCl₃ films through MXene modulation as an immense potential absorb layer for UV photodetector.