Asymmetric contact structure enables fast response of Bi2O2Se photodetectors

The near-infrared (NIR) photodetector is an important component in the realm of photodetectors. Bi2O2Se, with its narrow bandgap of 0.8 eV, has emerged as a promising candidate for NIR detection. However, it exhibits a slower response in this spectral region. An asymmetric electrode structure can effectively separate photogenerated electron–hole pairs by introducing an internal electric field, thereby facilitating faster carrier transport and significantly reducing the response time. In this study, we utilized PdSe2, a semi-metal, as an electrode to construct an asymmetric electrode structure in conjunction with Ti–Au electrode, aiming to enhance the performance of Bi2O2Se NIR photodetectors. The response time of the PdSe2/Bi2O2Se/Ti–Au photodetector was 21 and 16 μs under 1064 and 1550 nm light sources, respectively, with a responsivity of 121 mA/W at 1064 nm. These findings underscore the potential of this design in advancing infrared detection technology.