2D Metal Enabled Weak Fermi Level Pinning Effect and Tunable Charge Injection in Contacts with Inorganic 2D Perovskites.

Tow-dimensional (2D) perovskites have invoked extensive interest because of their good stability and intriguing optoelectronic properties. However, in practical applications, the hampered carrier transportation imposed by the vertical array of large dielectric organic cations and the generally seen Fermi level pinning (FLP) effect in conventional metal-2D semiconductors need to be solved urgently. Sb 3+ /Bi 3+ -based inorganic lead-free 2D Cs 3 (M 3+ ) 2 X 9 perovskites ( M = Sb 3+ , Bi 3+ ; X = Cl - , Br - , I - ) are promising candidates to replace the toxic 2D hLHP. The contact properties of Cs 3 Sb 2 Cl 9 with 2D metals are studied in this work to achieve tunable Schottky barrier heights (SBH). Density functional theory calculations reveal a weak FLP factor of 0.91 in the studied junctions, which is beneficial for improving the carrier injection efficiency through electrode design. Calculations of tunneling properties indicate that a Cd 3 C 2 electrode tends to achieve low SBH and high tunneling probability, while a VS 2 (H) electrode tends to realize high SBH and low tunneling probability, suggesting that diverse applications of Cs 3 Sb 2 Cl 9 can be achieved through electrode engineering.