) are the Fermi-Dirac distribution functions of an electron. The transmission function, T (E, V b ), were calculated using the Landauer-Büttiker formula: 51 The potential barrier of the 2D monolayer BA 2 SnI 4 -based device is nearly 50% larger than that of the 2D monolayer PEA 2 SnI 4 -based device (1.56 eV vs. 1.07 eV, Figure ).