Solution-Processed TiO2/CuBi2O4 Heterojunction for Self-powered Photodetection with Robust Environmental Resilience

Abstract

A solution-processed, efficient, self-powered, fast photodetector (PD) with the capacity to detect broadband light and withstand harsh environmental conditions will be a cost-effective solution for light sensing. Here, we explore the photophysical properties of spin-coated CuBi2O4 (CBO) thin films and report a self-powered broadband PD on all-oxide solution-processed TiO2/CBO heterojunction. The type-II band alignment between TiO2 and CBO facilitates the easy separation and movement of photogenerated charge carriers, enabling the device to work without any external power supply. The PD device shows a wide spectral response from 380 to 800 nm, along with good responsivity of 17.4 mA/W, and detectivity of 4.1 × 10^10 Jones, under 380 nm illumination, comparable to oxide-based PDs designed by physical vapor deposition. The device records quick rise and fall times of about 8 and 10 ms, respectively, indicating efficient charge transport at the interface. Furthermore, the device also exhibits strong environmental stability, maintaining its performance under varying humidity, temperature, and even underwater operation conditions. These results show the potential of TiO2/CBO heterojunction as a reliable and energy-efficient platform for self-powered optoelectronic devices and sensing applications.