Cyano‐Coordinated Tin Halide Perovskites for Wearable Health Monitoring and Weak Light Imaging

Abstract

Low‐toxicity tin halide perovskites with excellent optoelectronic properties are promising candidates for photodetection. However, tin halide perovskite photodetectors have suffered from high dark current owing to uncontrollable Sn2+ oxidation. Here, 2‐cyanoethan‐1‐aminium iodide (CNI) was introduced in CH(NH2)2SnI3 (FASnI3) perovskite films to inhibit Sn2+ oxidation by the strong coordination interaction between the cyano group (C≡N) and Sn2+. Consequently, FASnI3‐CNI films exhibited reduced non‐radiative recombination and lower trap density. The self‐powered photodetector based on FASnI3‐CNI exhibited low dark current (1.04×10−9 A cm−2), high detectivity (2.2×1013 Jones at 785 nm), fast response speed (2.62 µs) and good stability. Mechanism studies showed the increase in the activation energy required for thermal emission and generated carriers, leading to a lower dark current in the FASnI3‐CNI photodetector. In addition, flexible photodetectors based on FASnI3‐CNI, exhibiting high detectivity and fast response speed, were employed in wearable electronics to monitor the human heart rate under weak light and zero bias conditions. Finally, the FASnI3‐CNI perovskite photodetectors were integrated with a 32×32 thin‐film transistor backplane, capable of ultra‐weak light (170 nW cm−2) real‐time imaging with high contrast and zero power consumption, demonstrating the great potential for image sensor applications.This article is protected by copyright. All rights reserved

Research Progress of Cs-Based All-Inorganic Perovskite Solar Cells

“…There are also others who have conducted research in this area. Liu et al introduced 2-cyanoethylammonium iodide (CNI) into the halide tin-based perovskite film, using the strong coordination interaction between cyano (CeqN) and Sn 2+ to inhibit the oxidation of Sn 2+ , resulting in reduced non-radiative recombination and lower trap density in the perovskite film [49] (Figure 7B). Wang and his colleagues [50] attempted to introduce a suitable amount of multifunctional tin oxalate (SnC 2 O 4 ) to prepare efficient and stable Sn-Pb mixed IPSCs.…”