Enhanced‐Performance UV Photodetectors via Efficient Passivation of the SnO ₂ /Perovskite Interface Using Cl‐Terminated Mo _4/3 B _{2− x} MBene for High‐Definition Ultraviolet Imaging

Abstract The charge extraction capability and the quality of the absorber layer are critical factors that determine the performance of self‐powered ultraviolet photodetectors (UV PDs). However, the SnO ₂ electron transport layer (ETL) exhibits suboptimal performance in both electron extraction and high‐quality perovskite preparation. Herein, a novel 2D material, Cl‐terminated Mo _4/3 B _{2− x} MBene (Mo _4/3 B _{2− x} Cl _z ), is utilized to modify the SnO ₂ surface with the aim of enhancing charge extraction and optimizing the quality of CsPbCl ₃ films. The ‐Cl termination on MBene passivates oxygen vacancy defects on the SnO ₂ surface, significantly enhancing electron extraction efficiency. Furthermore, the loss of Cl ^‐ ions during CsPbCl ₃ film formation is compensated and the Pb ²⁺ is anchored, resulting in high‐quality perovskite films. The dual functionality of Mo _4/3 B _{2− x} Cl _z modification effectively mitigates nonradiative charge recombination at the SnO ₂ /CsPbCl ₃ interface. Ultimately, the UV PD featuring Mo _4/3 B _{2− x} Cl _z interface passivation achieves a responsivity of 1.05 × 10 ³ mA W ⁻¹ , a specific detectivity of 1.02 × 10 ¹² cm Hz ^1/2 W ⁻¹ , and exhibits rapid rise/decay times of 0.44/0.43 µs, respectively, under self‐powered mode, thereby enabling stable ultraviolet imaging. This research offers profound insights into the critical role of functionalized MBene in modulating the interface, facilitating the development of high‐performance UV PDs and promoting their practical applications.