The Regulation of Photoelectronic Property and Energy State of FAPbI3 Surface Via Ligand Dipole Design

Although the adding multifunction ligand can regulate the perovskite property, the effect of the enhancement depends on the ligand structure. In this paper, the polarity of aromatic ligand is regulated by design strategy — introducing fluorine (F) atom and alkyl chain (R-NH3). Those ligands affect the structure, photoelectric properties and energy state of formamidinium (FAPbI3) perovskite surface. The ligand polarity increases with more F atoms and R-NH3 length, which increases fermi energy and then decreasing band gap and increasing work function (WF). The CF3-PEA/BEA obtains the higher polarity and then increasing WF of the surface system from 6.21 eV to the higher 6.46 eV.