The UV–vis‐NIR Broadband Ultrafast Flexible Sn‐Pb Perovskite Photodetector for Multispectral Imaging to Distinguish Substance and Foreign‐Body in Biological Tissues

Abstract Multispectral imaging plays an important role in many applications such as color recognition, substance distinction, and medical therapy. Although multicolor detection has been demonstrated in lead‐based perovskites, the limited near‐infrared responsivity and slow response impede their applications for identifying the substance. Herein, narrow bandgap highly stable Cs 0.05 MA 0.45 FA 0.5 Sn 0.5 Pb 0.5 I 3 (Sn‐Pb) perovskite films with excellent crystallinity and selective growth orientation are realized by the synergy of a Sn‐Pb mixing method and electronegativity balance. The Sn‐Pb perovskite photodetector shows a broadband response from 350 to 1000 nm and high‐performance near‐infrared (NIR) detection with a fast response of 2.0 µs and excellent responsivity of 0.29 A W −1 . Furthermore, flexible Sn‐Pb perovskite devices without any encapsulation in the air continuously exhibit fast response after 3000 bending cycles. In addition, the Sn‐Pb perovskite diffuse reflection imaging system is demonstrated for multispectral imaging and substance distinction. Meanwhile, foreign‐body identification in biological tissues by NIR imaging of Sn‐Pb perovskite photodetectors is further demonstrated, proving narrow bandgap mixed perovskite photodetectors an attractive candidate for biomedical imaging.