Stable, Semitransparent, and Self‐Powered Conjugated‐Polymer/CsPbI₂Br UV–vis–NIR Photodetector Improved by Thiamine Additive

Abstract Transparent/semitransparent perovskite photodetectors hold great promise for next‐generation optoelectronic devices due to their attractive photoelectric properties and transparency. However, most previously reported transparent perovskite photodetectors require an external power supply and are unstable under relatively high humidity ambient conditions. To address these issues and realize improved performance, this study demonstrates a semitransparent self‐powered broad photodetector based on an inorganic CsPbI₂Br perovskite/conjugated‐polymer hybrid structure with a thiamine hydrochloride additive. By optimizing the concentration of the thiamine hydrochloride additive, the main crystal exposure of the CsPbI₂Br film changes from the (200) to the (110) plane orientation and can remain stable for more than 10 d in the air with 60%–70% humidity. The corresponding device exhibits a broad response spectrum up to a wavelength of 950 nm, a fast response speed (200/580 µs), a high responsivity (0.32 A W⁻¹), and a large detectivity (4.4 × 10¹³ Jones). The improvement is mainly due to thiamine hydrochloride controlling the crystal growth to realize the desired crystal plane orientation and reduce the crystal size, which in turn improves the phase stability and optoelectronic properties of CsPbI₂Br.