Sol-Gel Cupric Oxide Thin Film Transistors: Alkali Metal Doping for Low Temperature Flexible Devices

Solution-processed copper oxide (Cu
x
O) semiconductors have gained significant interest in recent years due to their p-type conductivity, transparency, nontoxicity, and low cost. However, the development of Cu
x
O thin film transistors (TFTs) has been limited by their low field-effect mobility and poor reproducibility. In this study, we present a simple solution doping process for producing high-performance sol-gel-based CuO TFTs under ambient conditions. By doping the precursor solution with an alkali metal, we achieved a more than 10-fold increase in device mobility compared to pristine CuO transistors annealed at the same temperature. These results suggest the possibility of implementing solution processed p-type oxide transistors at lower temperatures, thereby enabling CuO TFTs to be realized on flexible plastic substrates.