High-Sensitivity and Fast-Response Self-Powered Photodetectors Based on Lead-Free CsBi₃I 1₀/TiO₂ Heterojunction

Self-powered photodetectors (SPPDs) based on halide perovskites have aroused interest owing to their high sensitivity, low power consumption, and integrability without an external power source. However, lead halide perovskites are mainly used in the previously reported photodetectors, which hinders their further development owing to the toxicity of lead. Herein, SPPDs based on lead-free perovskites CsBi3I10/TiO2 heterojunction are designed. The built-in electric field in the CsBi3I10/TiO2 heterojunction offers a driving force for separating and transporting photoexcited charge carriers. In the self-powered mode, the photodetector can respond to light as weak as 0.15 nW
$\cdot $
cm
$^{-{2}}$
, achieving a high photoresponsivity (0.35 A
$\cdot $
W
$^{-{1}}\text {)}$
and good detectivity (
$2.0\times 10^{{12}}$
Jones). Moreover, the photodetector exhibits a fast response/recovery time (48/
$58~\mu $
s) and a wide linear dynamic range (LDR) of 127 dB, and the unpackaged photodetector holds good stability, including air stability, operational stability, and illumination stability. This work suggests that the simple combination of lead-free perovskites and an electron-transporting material possesses great potential for low-power consumption photoelectrical applications.