Ferroelectric Wide‐Bandgap Metal Halide Perovskite Field‐Effect Transistors: Toward Transparent Electronics

Abstract Transparent field‐effect transistors (FETs) are attacking intensive interest for constructing fancy “invisible” electronic products. Presently, the main technology for realizing transparent FETs is based on metal oxide semiconductors, which have wide‐bandgap but generally demand sputtering technique or high‐temperature (>350 °C) solution process for fabrication. Herein, a general device fabrication strategy for metal halide perovskite (MHP) FETs is shown, by which transparent perovskite FETs are successfully obtained using low‐temperature (<150 °C) solution process. This strategy involves the employment of ferroelectric copolymer poly(vinylidene fluoride‐co‐trifluoroethylene) (PVDF‐TrFE) as the dielectric, which conquers the challenging issue of gate‐electric‐field screening effect in MHP FETs. Additionally, an ultra‐thin SnO 2 is inserted between the source/drain electrodes and MHPs to facilitate electron injection. Consequently, n‐type semi‐transparent MAPbBr 3 FETs and fully transparent MAPbCl 3 FETs which can operate well at room temperature with mobility over 10 −3 cm 2 V −1 s −1 and on/off ratio >10 3 are achieved for the first time. The low‐temperature solution processability of these FETs makes them particularly attractive for applications in low‐cost, large‐area transparent electronics.