Layer-Dependent Ultrahigh-Mobility Transport Properties in All-Inorganic Two-Dimensional Cs2PbI2Cl2 and Cs2SnI2Cl2 Perovskites

摘要

Recently, novel inorganic two-dimensional (2D) Cs2PbI2Cl2 and Cs2SnI2Cl2 perovskites were reported, exhibiting excellent stability and superior optoelectronic properties. Because it has been suggested that perovskites based on light elements such as Cl or Sn would display high charge carrier mobility, 2D Cs2PbI2Cl2 and Cs2SnI2Cl2 are considered promising 2D materials with high carrier mobility because of the in-plane Pb-Cl and Sn-Cl framework. Here, we present a detailed theoretical investigation of the optoelectronic properties of newly fabricated 2D Cs2PbI2Cl2 and Cs2SnI2Cl2 and predict rather high, layer-dependent in-plane electron- and hole-dominated carrier mobilities for 2D Cs2PbI2Cl2 and Cs2SnI2Cl2, respectively, based on deformation potential theory. The predicted hole mobility for trilayer Cs2SnI2Cl2 (as high as similar to 1.39 x 10(4) cm(2) V-1 s(-1)) and electron mobility for bilayer Cs2PbI2Cl2 (as high as similar to 9.39 x 10(3) cm(2) V-1 s(-1)) are much higher than those of the known halide perovskites and are comparable to those of black phosphorus. Additionally, the wide and direct band gaps, small effective masses, and low exciton binding energies of 2D Cs2PbI2Cl2 and Cs2SnI2Cl2 ensure their potentials as promising candidates for future electronics.