A Lewis base and boundary passivation bifunctional additive for high performance lead-free layered-perovskite transistors and phototransistors

ABSTRACT Halide perovskite semiconductors exhibit low intrinsic effective mass of charge carrier, however, their development of transistors is lagging far behind the development of photovoltaic and light-emitting diodes. In this study, we report highly reproducible phenethylammonium tin iodide transistors with a mobility over 4 cm2 V-1 s-1 and an on/off ratio over 105 using a simple method of adding a bifunctional additive, urea, into the precursor. This non-volatile Lewis base can modify the crystallisation speed and passivate grain-boundary defects, enabling significant improvement in the transistor characteristics over pristine devices without urea. Furthermore, we demonstrate unprecedented phototransistor characteristics, with a detectivity exceeding 1017 Jones when the improved perovskite transistors are used. It is expected that more intensive efforts can be attracted to advance the development of high-performance perovskite (photo)transistors.