Antimony selenide (Sb₂Se₃) has recently made considerable advancements in photovoltaic, photoelectrochemical, and photodetector research scenarios, owing to its advantageous material merits and superior optoelectronic properties. By contrast, the exploration of flexible Sb₂Se₃ photoelectric devices are less attempted, though it possesses unique one-dimensional (1D) crystal structure to enable large deformation tolerance. Here, we develop a flexible Sb₂Se₃ thin-film photodetector on polyimide substrate. Thanks to the high-quality Sb₂Se₃ light absorber and benign interfaces at both back contact and heterojunction regions, the carrier dynamics are effectively optimized. The leading flexible Sb₂Se₃ photodetector showcases self-powered and broadband features, with exceptional responsivity of 0.51 A W^–1 and realistic detectivity up to 1.32 × 10¹³ Jones, ultra-fast response speed of 49/351 ns of rise and decay times, and remarkable mechanical deformation stability, flourishing the high-level development for flexible Sb₂Se₃ photodetectors. Interestingly, a tunable single/dual-color flexible imaging system under band alignment modulation, along with a wearable and accurate heart rate/arterial blood oxygen saturation photoplethysmography detection system highlights the great application potential for flexible Sb₂Se₃ photodetectors.

Antimony selenide (Sb₂Se₃) semiconducting material possesses a band gap of 1.05–1.2 eV and has been widely applied in single-junction solar cells. Based on its band gap, Sb₂Se₃ can also be used as the bottom cell absorber material in tandem solar cells. More importantly, Sb₂Se₃ solar cells exhibit excellent stability with nontoxic compositional elements. The band gap of organic–inorganic hybrid perovskite is tunable over a wide range. In this work, we demonstrate for the first time a perovskite/antimony selenide four-terminal tandem solar cell with a specially designed and fabricated transparent electrode for an optimized spectral response. By adjusting the thickness of the transparent electrode layer of the top cell, the wide-band-gap perovskite top solar cell achieves an efficiency of 17.88%, while the optimized antimony selenide bottom cell delivers a power conversion efficiency of 7.85% by introducing a double electron transport layer. Finally, the four-terminal tandem solar cell achieves an impressive efficiency exceeding 20%. This work provides a new tandem device structure and demonstrates that antimony selenide is a promising absorber material for bottom cell applications in tandem solar cells.