Enhanced-Performance UV Photodetectors via Efficient Passivation of the SnO₂/Perovskite Interface Using Cl-Terminated Mo_4/3B_2−x MBene for High-Definition Ultraviolet Imaging

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 SnO₂ electron transport layer (ETL) exhibits suboptimal performance in both electron extraction and high-quality perovskite preparation. Herein, a novel 2D material, Cl-terminated Mo_4/3B_2−x MBene (Mo_4/3B_2−xCl_z), is utilized to modify the SnO₂ surface with the aim of enhancing charge extraction and optimizing the quality of CsPbCl₃ films. The -Cl termination on MBene passivates oxygen vacancy defects on the SnO₂ surface, significantly enhancing electron extraction efficiency. Furthermore, the loss of Cl^- ions during CsPbCl₃ film formation is compensated and the Pb²⁺ is anchored, resulting in high-quality perovskite films. The dual functionality of Mo_4/3B_2−xCl_z modification effectively mitigates nonradiative charge recombination at the SnO₂/CsPbCl₃ interface. Ultimately, the UV PD featuring Mo_4/3B_2−xCl_z interface passivation achieves a responsivity of 1.05 × 10³ mA W⁻¹, a specific detectivity of 1.02 × 10¹² 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.