High-performance p-channel CuIBr thin-film transistor synthesized from solution in the atmosphere

The p-type transparent semiconductor CuI has a high potential to be used in thin film transistors (TFTs) due to high hole mobility and solution processability. However, the lower copper vacancy formation energy and the subsequent high hole concentration in CuI lead to a low on/off current ratio (ION/IOFF) for CuI TFT devices. The density functional theory results suggest that the copper vacancy formation energy increases with the CuBr content in the Br-doped CuI film, resulting in lower hole concentration. Alloying CuI with CuBr is proposed to reduce the hole concentration in the CuIBr alloy. The CuIBr TFTs with Br content ranging from 0% to 10% were fabricated using the solution method. It is found that the hole mobility decreases from 8 to 1 cm2 V−1 s−1, while the ION/IOFF ratio increases from 102 to 104 with the increasing Br content. The CuIBr TFT with 7.5% Br content exhibits a high hole mobility larger than 5 cm2 V−1 s−1 and high ION/IOFF ratio of 104, which paves the way for inorganic-based CMOS circuits on flexible and transparent substrates.