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

Chitosan (CS) dielectrics are in favor of packed CuI films with tiny grains on them under a robust ambient conditions, and hence facilitate transparent and flexible p-type CuI thin-film transistors with high mobility and on/off current ratio. Complementary inverters based on the CuI transistors demonstrate a voltage gain over 20. [Display omitted] • Flexible/transparent p-Type CuI TFTs are constructed, with μ FE up to 65 cm2V−1s−1 and I on / I off of 104. • Chitosan dielectrics facilitate easy coating of high-quality CuI films under permissive conditions. • Complementary inverters are demonstrated by combining p-type CuI and n -type ITO TFTs. 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 SiO 2 dielectric with Chitosan (CS, a kind of solid polymer electrolytes), with the threshold voltage down to −0.35 V, field-effect mobility (μ FE) up to 60 cm2V−1s−1 and on/off current ratio (I on / I off) 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 μ FE , in sharp contrast with the SiO 2 case. In addition, the CuI films on CS-dielectrics demonstrate a work function ∼ 0.1 eV lower than that on SiO 2 , which implies a smaller hole concentration and higher I on / I off. And the low process temperature (<50 °C) facilitates the achievement of flexible and transparent CuI TFTs with μ FE and I on / I off comparable to those on rigid InSnO (ITO) glass. Furthermore, complementary inverters composed of p-type CuI and n -type ITO TFTs are demonstrated with clear inverting characteristics and voltage gain of over 20. [ABSTRACT FROM AUTHOR]