Abstract

Abstract Short‐wave infrared (SWIR) photodetectors utilizing quantum dot (QD) material systems, harnessed through the quantum confinement effect to tune the absorption wavelength, offer an attractive avenue for the development of cost‐effective and solution‐processed photodetectors compared to the relatively expensive compound semiconductor photodetectors. However, the pores between the QDs and poor chemical stability after surface modification have impeded the practical application of quantum‐dot‐based photodetectors. In this study, high‐gain SWIR photodetector is demonstrated and achieved by incorporating PbS QD into the Cs 2 AgBiBr 6 halide‐based double perovskite matrix, as confirmed by X‐ray diffraction, transmission electron microscope, and energy dispersive spectrometer. The thin film structure and detailed local structure are revealed by 2D grazing‐incidence wide and small‐angle X‐ray scattering. The resulting PbS@Cs 2 AgBiBr 6 ‐based SWIR photodetector exhibits remarkable performance with a responsivity and detectivity of 15000 A W −1 and 1.31 × 10 12 cm Hz 1/2 W −1 , respectively. This study offers valuable insights into the design of composite materials for high‐gain SWIR photodetectors.