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

Two-dimensional(2D) PbI_2 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 PbI_2 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 PbI_2 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 PbI_2 flakes with the average size of 5 mm and thickness of 17 nm. Moreover, as-fabricated PbI_2-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(1.04×10^(10) Jones). The well-controllable growth of the uniform triangle PbI_2 flakes and the detailed exploration of their optoelectronic properties are particularly valuable for their further practical applications.

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 μm and thickness of 17 nm. Moreover, as-fabricated PbI2-based photodetectors show promising stable and flexible optoelectronic performances to ,170 nm light, including high responsivity （0.72 A W ^-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 × 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.