Efficient Carrier Transport in 2D Bi2O2Se/CsBi3I10 Perovskite Heterojunction Enables Highly‐Sensitive Broadband Photodetection

Abstract 2D Bi 2 O 2 Se has recently garnered significant attention in the electronics and optoelectronics fields due to its remarkable photosensitivity, broad spectral absorption, and excellent long‐term environmental stability. However, the development of integrated Bi 2 O 2 Se photodetector with high performance and low‐power consumption is limited by material synthesis method and the inherent high carrier concentration of Bi 2 O 2 Se. Here, a type‐I heterojunction is presented, comprising 2D Bi 2 O 2 Se and lead‐free bismuth perovskite CsBi 3 I 10 , for fast response and broadband detection. Through effective charge transfer and strong coupling effect at the interfaces of Bi 2 O 2 Se and CsBi 3 I 10 , the response time is accelerated to 4.1 µs, and the detection range is expanded from ultraviolet to near‐infrared spectral regions (365–1500 nm). The as‐fabricated photodetector exhibits a responsivity of 48.63 AW −1 and a detectivity of 1.22×10 12 Jones at 808 nm. Moreover, efficient modulation of the dominant photocurrent generation mechanism from photoconductive to photogating effect leads to sensitive response exceeding 10 3 AW −1 for heterojunction‐based photo field effect transistor (photo‐FETs). Utilizing the large‐scale growth of both Bi 2 O 2 Se and CsBi 3 I 10 , the as‐fabricated integrated photodetector array demonstrates outstanding homogeneity and stability of photo‐response performance. The proposed 2D Bi 2 O 2 Se/CsBi 3 I 10 perovskite heterojunction holds promising prospects for the future‐generation photodetector arrays and integrated optoelectronic systems.