Approaching Theoretical Limits in The Performance of Printed P-Type Cui Transistors via Room Temperature Vacancy Engineering.

Development of a novel high performing inorganic p-type thin film transistor could pave the way for new transparent electronic devices. This complements the widely commercialized n-type counterparts, indium gallium zinc oxide (IGZO). Of the few potential candidates, copper monoiodide (CuI) stands out. It boasts visible light transparency and high intrinsic hole mobility (> 40 cm 2 V -1 s -1 ), and is suitable for various low-temperature processes. However, the performance of reported CuI transistors is still below expected mobility, mainly due to the uncontrolled excess charge- and defect-scattering from thermodynamically favoured formation of copper and iodine vacancies. Here, we report a solution-processed CuI transistor with a significantly improved mobility. This enhancement is achieved through a room-temperature vacancy-engineering processing strategy on high-k dielectrics, sodium-embedded alumina (SEA). A thorough set of chemical, structural, optical and electrical analyses elucidates the processing-dependent vacancy-modulation and its corresponding transport mechanism in CuI. This encompasses defect- and phonon-scattering, as well as the delocalization of charges in crystalline domains. As a result, the optimized CuI thin film transistors exhibit exceptionally high hole mobility of 21.6 ± 4.5 cm 2 V -1 s -1 . Further, successful operation of IGZO-CuI complementary logic gates confirms applicability of our device. This article is protected by copyright. All rights reserved.