Piezo-Phototronic Enhancement of Vertical Structure Photodetectors Based on 2D CsPbBr3 Nanosheets

Abstract

Two-dimensional (2D) CsPbBr3 have received great interest in flexible photoelectric devices due to their excellent carrier mobility and tunable optical bandgap. However, it is unknown if the piezo-phototronic effects of a vertically structured 2D CsPbBr3 photodetector affect its photoelectric performance. Herein, we fabricated a vertical structure device based on 2D CsPbBr3 by using conductive atomic force microscopy and then probed its photoelectric performances under different forces. The photocurrent and on/off ratio under 450 nm laser illumination rise by up to 2.1 and 5.3 times, respectively, when the applied force is 30 nN as compared with that under 10 nN. To investigate the mechanism underlying the enhancement of photoelectric performance, piezoelectric force microscopy measurement and density functional theory calculation were used to estimate the vertical piezoelectric coefficient of 2D CsPbBr3, which were found to be 7.3 pm/V and 3.8 pm/V, respectively. The enhancement of performances can be attributed to the piezo-phototronic effect of 2D CsPbBr3, which increases the separation of photogenerated holes at the interface. These findings propose a comprehensive strategy for enhancing photoelectric performance through piezo-phototronic effects in piezoelectric-based photoelectric devices with vertical structures.