Passivation of PEA+ to MAPbI3 (110) surface states by first-principles calculations*

The MAPbI 3 (110) surface with low indices of crystal face is a stable and highly compatible photosensitive surface. Since the electronic states on the surface can be detrimental to the photovoltaic efficiency of the device, they should be passivated. Phenylethylamine (PEA + ), as a molecular ligand, has been widely used in continuous degradation and interfacial charge recombination experiments, and has satisfactory performance in improving surface defects. Therefore, we construct an adsorption model of MAPbI 3 with small molecules, calculating the lattice structure and electronic properties of PEA + -adsorbed MAPbI 3 (110) surface. It is found that PEA + as a passivator can effectively weaken the electronic states and regulate the band gap of the MAPbI 3 (110) surface. Before and after adding the passivator, the peak value of electronic state densities at MAPbI 3 (110) surface is reduced by about 50%, and the band gap is apparently reduced. Moreover, by comparing the Bader atomic charge and spatial charge distributions before and after PEA + ’s adsorption on the surface of MAPbI 3 , we observe a substantial change of PEA + charges, which suggests the surface states have been passivated by PEA + .