High-mobility flexible/transparent p-type copper iodide thin-film transistors and complementary inverters

High-performance transparent and low-process-temperature p-type devices are essential for portable and ‘invisible’ electronics. In this work, high-performance p-channel copper iodide (CuI) thin-film transistors (TFTs) with a bottom-gate structure are achieved via replacing traditional SiO2 dielectric with Chitosan (CS, a kind of solid polymer electrolytes), with the threshold voltage down to −0.35 V, field-effect mobility (μFE) up to 60 cm2V−1s−1 and on/off current ratio (Ion/Ioff) beyond 103. The CuI films spin-coated on CS-dielectrics in the air with high humidity have smoother surface morphology, tinier grains, higher packing density and hence a higher μFE, in sharp contrast with the SiO2 case. In addition, the CuI films on CS-dielectrics demonstrate a work function ∼ 0.1 eV lower than that on SiO2, which implies a smaller hole concentration and higher Ion/Ioff. And the low process temperature (