Effects of solution processable CuI thin films with Al₂O₃-based sandwiched architecture for high-performance p-type transistor applications

Copper iodide (CuI) has been in the spotlight as a promising p-type semiconducting material due to its excellent electrical property and low fabrication temperature. Here, we propose a novel approach for constructing solution-processable p-type CuI TFTs sandwiched by both Al2O3 interfacial and passivation layers and demonstrate the improvement mechanism for device performance. The pristine CuI TFTs with optimized Al2O3-based sandwiched architecture exhibited enhanced device performance, such as a high current on-off ratio of 1.01 x 10(5), a low hysteresis of 0.76 V, and a subthreshold swing of 0.35 V decade(-1). These parameters exceed the performance of CuI TFTs in previous reports to the best of our knowledge. We further systematically studied the effective roles of the Al2O3-based sandwiched architecture, inducing the creation of the iodine vacancy and decrease in the hole concentration, as well as improved crystallinity and grain size. Based on the results, high-performance CuI TFTs with excellent stability were achieved, sustaining the electrical performance after repeated operation over 100 times. Thus, this work can provide a new insight on solution-processable p-type CuI TFTs with Al2O3-based sandwiched architecture for developing high-performance complementary logic circuits.