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 Cs0.05MA0.45FA0.5Sn0.5Pb0.5I3 (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.

Regulating energy band alignment for high-performance broadband perovskite photodetectors

“…4i compares the wavelength-dependent D * and R in the infrared band. 1,20–24,62,63,69–92 Compared with the previous research on broadband photodetectors, this work exhibits longer wavelength detection. In particular, the photodetector exhibits a leading detection performance over 1000 nm.…”

Near‐infrared emitting metal halide materials: Luminescence design and applications

“…The mixed Sn-Pb halide perovskites have been widely developed in photodetectors in view of their stability and adjustable bandgaps, which extend the detected light to longer wavelength NIR region. 305,306,308 For example, an efficient NIR detector fabricated by MAPb 0.5 Sn 0.5 I 3 showed a responsivity of 0.51 A W À1 and a specific detectivity of 1.5 Â 10 11 Jones under 905 nm light illumination and À1 V bias. 309 Notably, this NIR detector had obvious photoresponse at zero bias with a responsivity of 0.0016 A W À1 as well as a detectivity of 3.08 Â 10 10 Jones.…”