One-Dimensional Sb₂Se₃ Enabling a Highly Flexible Photodiode for Light-Source-Free Heart Rate Detection

Abstract

Accurate, real-time, and noninvasive monitoring of health signals, such as heart rate, is indispensable for mobile health care. A highly sensitive and flexible photoelectric detector is the key component for collection of biological signals. Herein, a Sb2Se3-based photodiode is fabricated on a flexible polyimide substrate. The device exhibited impressive detection performance with 95 dB linear dynamic range, 83% external quantum efficiency, 0.42 A W–1 photoresponsivity, less than 10–14 A Hz–1/2 noise current, and 500 kHz −3 dB bandwidth. Moreover, thanks to the 1D crystal structure of Sb2Se3, our devices demonstrate ultrahigh flexibility with negligible performance degradation after bending at 69° for a 1000× cycle. Owing to these decent features, the flexible Sb2Se3 photodiodes are employed for additional light-source-free heart rate detection. This work opens up an avenue toward wearable Sb2Se3-based photoelectric devices, such as flexible solar cells.