Regulating energy band alignment for high-performance broadband perovskite photodetectors

Abstract

The Sn–Pb mixed perovskite, renowned for its narrow band gap and exceptional photoelectric properties, has garnered significant attention in photodetection, particularly as a potential alternative to near-infrared materials. However, the photodetector often suffers from unfavorable energy band arrangements at the heterogeneous interface between the perovskite and the electrode, which seriously hinder the further improvement of device performance. Here, a broadband, high-performance photodetector based on the Sn–Pb mixed perovskite has been achieved through fine-tuning of the energy band alignment at the perovskite/electrode interface. The resultant photodetector demonstrates an impressive broadband response spanning 367 to 1200 nm. At 395 nm, it achieves remarkable metrics: an ultra-high responsivity of 1.2 × 10³ A W⁻¹ and an outstanding detectivity of 4.4 × 10¹³ Jones, accompanied by a fast rise/fall time of 2.4 ms/5.4 ms. In particular, the sub-bandgap states of the Sn–Pb mixed perovskite enable the photoresponse beyond the bandgap limit. At 1200 nm, its responsivity and detectivity reach leading levels of 24.73 A W⁻¹ and 1.01 × 10¹² Jones, respectively. Moreover, it exhibits exceptional flexibility, enduring over 500 bending cycles without encapsulation while maintaining a decent photoelectric response. These findings underscore the critical role of optimizing interface contact in realizing high-performance, broadband perovskite photodetectors.