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

Recently, novel inorganic two-dimensional (2D) Cs2PbI2Cl2 and Cs2SnI2Cl2 perovskites were reported exhibiting excellent stability and superior optoelectronic properties. Since 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 due to 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 (DP) theory. The predicted hole mobility for trilayer Cs2SnI2Cl2 (as high as ~1.39×104 cm2 V-1 s-1) and electron mobility for bilayer Cs2PbI2Cl2 (as high as ~9.39×103 cm2 V-1 s-1) are much higher than those of the known halide perovskites, and are comparable to blac...