P-type CuO and Cu₂O transistors derived from a sol-gel copper (II) acetate monohydrate precursor

We realize p-type thin film transistors (TFT) with solution-processed channels using a sol-gel route, based on a copper (II) acetate precursor. The sol-gel process initially produces Cu, which is then oxidized depending on sintering conditions to produce Cu₂O and ultimately CuO. These processes are performed at temperatures no higher than 500 °C, and are therefore compatible with standard display glass substrates for use in transparent display applications. To control the film morphology of the sol-gel processed copper oxide layer, additional water was added to the precursor solution. As the water to alkoxide ratio is increased, the degree of hydrolysis increased, thus increasing the grain size of CuO and Cu₂O. The resulting p-type CuO and Cu₂O TFTs exhibited improved thin film transistor performance, including field effect mobilities of 1.0 × 10^{- 2} cm²/Vs and 2.0 × 10^{- 3} cm²/Vs, respectively, and an on/off ratio of approximately 10³.