Flexoelectric Engineering of Bulk Photovoltaic Photodetector
Junxi Yu, Boyuan Huang, Songjie Yang, Yuan Zhang, Yinxin Bai, Chunlin Song, Wenjie Ming, Wenyuan Liu, Junling Wang, Changjian Li, Qingyuan Wang, Jiangyu Li
Abstract
The bulk photovoltaic effect (BPVE) offers an interesting approach to generate a steady photocurrent in a single-phase material under homogeneous illumination, and it has been extensively investigated in ferroelectrics exhibiting spontaneous polarization that breaks inversion symmetry. Flexoelectricity breaks inversion symmetry via a strain gradient in the otherwise nonpolar materials, enabling manipulation of ferroelectric order without an electric field. Combining these two effects, we demonstrate active mechanical control of BPVE in suspended 2-dimensional CuInP 2 S 6 (CIPS) that is ferroelectric yet sensitive to electric field, which enables practical photodetection with an order of magnitude enhancement in performance. The suspended CIPS exhibits a 20-fold increase in photocurrent, which can be continuously modulated by either mechanical force or light polarization. The flexoelectrically engineered photodetection device, activated by air pressure and without any optimization, possesses a responsivity of 2.45 × 10 –2 A/W and a detectivity of 1.73 × 10 11 jones, which are superior to those of ferroelectric-based photodetection and comparable to those of the commercial Si photodiode.