A Computational Characterization of 2,2′-bis(trifluoromethyl)-[1,1′-biphenyl]-4,4′-diamine Iodine Dopant for Improving Power-Conversion Efficiency of Perovskite Solar Cells

The paper presents ongoing density-functional theory (DFT) computational support to research of hybrid perovskite solar cells to facilitate their understanding at molecular level. Very recently, doping by a iodine salt, namely 2,2′-bis(trifluoromethyl)-[1,1′-biphenyl]-4,4′-diamine iodine BFBAI₂, has been described that improves the power conversion efficiency and enhances device stability. As structural characteristics of BFBAI₂ are not well known, they are supplied here through DFT calculations for both BFBAI₂ monomer and dimer. The geometry optimizations are performed at the M06-2X/3-21G level, and energetics is refined with the M06-2X/Def2QZVP treatment. The dimerization potential-energy change is calculated as −6.2 kcal/mol. BFBAI₂ exhibits highly non-uniform charge distribution, i.e., it is a clearly polar system that can strongly modulate surface conditions when adsorbed. The adsorption-energy gain for BFBAI₂ on CsPbI₃ perovskite is DFT evaluated as −13.2 kcal/mol.