A high-performance self-powered CsPbBr3 perovskite photodetector enabled by self-assembled monolayer interface engineering

Abstract

Metal halide perovskites have emerged as promising candidates for self-powered photodetectors due to their exceptional optoelectronic properties, including low exciton binding energies, high absorption coefficients, superior charge transport properties, and solution processability. However, the inherent high dark current in perovskite-based devices remains a fundamental limitation to their performance. In this study, we present an interface engineering strategy to overcome this challenge by incorporating a self-assembled monolayer (SAM) between the TiO_x electron transport layer and the CsPbBr₃ perovskite quantum dot film. Comprehensive experimental analysis indicates that the SAM layer performs a critical dual function: it effectively blocks interfacial electron injection as a charge barrier and promotes higher quality perovskite films through crystallinity optimization and defect passivation, ultimately suppressing non-radiative recombination. This synergistic effect results in a reduction of dark current to an ultralow value of 2.13 × 10⁻¹⁰ A. The optimized photodetector exhibits high-performance metrics at zero bias under 365 nm illumination, achieving an outstanding on/off ratio of 7.6 × 10⁶, a high specific detectivity of 2.74 × 10¹² Jones, and an extensive linear dynamic range of 137.7 dB. Furthermore, the device demonstrates exceptional environmental stability, maintaining 91.8% of its initial efficiency after 120 days of storage in a nitrogen atmosphere without encapsulation. This work establishes a universal approach for defect suppression in perovskite optoelectronics, with potential applications extending to solar cells, light-emitting diodes, and radiation detectors.