Solution‐Processed Monolithic CH3NH3PbI3/PbI2 Vertical Heterostructure for High‐Performance Flexible and Broadband Photodetector

Abstract 2D semiconductors are attracting increasing interest owing to their promising applications in high‐performance photodetection. However, the spectral response window is dictated by their intrinsic bandgaps, which is typically narrow and severely hinders their applications as broadband photodetectors. Herein, taking advantage of the outstanding optoelectronic properties of perovskite and 2D materials, a monolithic 2D CH 3 NH 3 PbI 3 /PbI 2 vertical heterostructure is synthesized via a facile two‐step solution method at room temperature, and flexible photodetectors based on the CH 3 NH 3 PbI 3 /PbI 2 heterostructures are constructed. The photodetectors with excellent flexibility and stability exhibit light response under various laser wavelengths from 375 to 1342 nm. In particular, the photodetector shows a current on/off ratio of ≈10 3 , a high detectivity up to 1.66 × 10 12 Jones, a responsivity of 4.79 A W −1 , and a response speed of 16 ms under 375 nm illumination. This work provides a facile route to 2D vertical semiconducting heterostructures, which is promising for application in high‐performance integrated optoelectronics.