Oxygen Vacancies Driven Photoconductivity in Layered Cobaltite Epitaxial Films

Understanding photoinduced phenomena in complex oxides is crucial for developing next‐generation optoelectronic devices. Here, we report pronounced ultraviolet (UV) light‐induced photoconductivity in epitaxial PrBa 1‐x Ca x Co 2 O 5+δ (x = 0.5) thin films grown on (001) LSAT substrates via pulsed laser deposition. Following controlled post‐annealing to induce oxygen deficiency, the oxygen‐deficient films exhibit a 1.35‐fold enhancement in photoresponse compared to oxygen‐rich counterparts under 365 nm illumination with a power density of 60 mW cm −2 . This enhanced photoresponse originates from increased carrier density due to the trapping of photoexcited electrons at oxygen vacancies, and the photoresponse behavior is highly tunable by both pulse width and light density. Notably, the oxygen‐deficient films demonstrate paired‐pulse facilitation (PPF) behavior under 1 s excitation pulse, and the photoresponse remains almost constant even when the readout voltage is reduced by two orders of magnitude down to 1 mV. These findings highlight the potential of cobaltite oxides as promising platforms for low‐power, light‐tunable oxide electronics and UV photonic sensors.