Trap Assisted Persistent Photo-Conductivity in Solution-Processed CuO Thin Film

Optically induced meta-stable states in the semiconductor lattice temporarily change the conductivity which leads to a phenomenon called persistent photo-conductivity (PPC). We report a PPC effect with long retention time of more than 90 h in solution-processed highly transparent CuO thin film. A 254 nm wavelength light source was used to `set' and thermal annealing at 50°C for 10 minutes and NIR illumination was used to reset PPC effect. Activated trap states without any stimulus which are responsible for PPC effect in CuO thin film has, been investigated by performing temperature-dependent I-V characterization. These trapped charges are released either on heating or illumination with NIR light source. Such a long-enduring PPC achieved in low-cost transparent CuO thin film could pave the way for further study of the feasibility of optically defined, transparent electronics.