Achieving highly uniform two-dimensional PbI2 flakes for photodetectors via space confined physical vapor deposition

Two-dimensional (2D) PbI2 flakes have been attracting intensive attention as one potential candidate for the modern optoelectronics. However, suffered from the instability of kinetics-driven growth, the fabricated 2D PbI2 flakes have a wide dimensional distribution even under the same conditions. Herein, a novel facile space confined physical vapor deposition (PVD) process is provided to synthesize uniform triangle PbI2 flakes with high quality. The confined space provides a relatively stable growth environment that renders more control on the growth kinetics, leading to highly uniform triangle PbI2 flakes with the average size of 5 mu m and thickness of 17 nm. Moreover, as-fabricated PbI2-based photodetectors show promising stable and flexible optoelectronic performances to 470 nm light, including high responsivity (0.72 AW(-1)), large on/off ratio up to 900, fast photoresponse speed (rise time of 13.5 ms and decay time of 20 ms) and high detectivity (1.04 x 10(10) Jones). The well-controllable growth of the uniform triangle PbI2 flakes and the detailed exploration of their optoelectronic properties are particularly valuable for their further practical applications. (C) 2017 Science China Press. Published by Elsevier B.V. and Science China Press. All rights reserved.