Photodetector Based\non Elemental Ferroelectric Black\nPhosphorus-like Bismuth

Two-dimensional ferroelectric materials have emerged\nas a promising\ncandidate for the development of next-generation photodetectors owing\nto their inherent photogalvanic effect (PGE) and strong light–matter\ninteractions. Recently, the first-ever elemental-based ferroelectric\nmaterial, black-phosphorus-like Bi (BP-Bi), has been successfully\nsynthesized. In this work, we investigate the PGE of the monolayer\n(ML) BP-Bi by using ab initio quantum transport simulation. We find\nthat the photocurrent of the ML BP-Bi in the ferroelectric direction\n(armchair) is significantly larger than that in the vertical ferroelectric\ndirection [zigzag (ZZ)]. For example, despite the comparable optical\nabsorption rates of BP-Bi in the armchair (ARM) and ZZ directions,\nthe maximum photocurrent (133 mA/W) in the ARM direction is 2 orders\nof magnitude greater than that (4.70 mA/W) in the ZZ direction. The\nasymmetry is attributed to the breaking and existence of the mirror\ninversion symmetries along the ARM and ZZ directions, respectively.\nOur work paves the way for the research of the low-dimensional ferroelectric\nphotodetector.