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

Abstract

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.

A Note on Stability of a Dopant for Perovskite Solar Cells: Dimerization of 2,2′-bis(trifluoromethyl)-[1,1′-biphenyl]-4,4′-diamine Iodine

“…[1][2][3] Recently, doping with a iodine salt, viz. 2,2′-bis(trifluoromethyl)-[1,1′-biphenyl]-4,4′-diamine iodine (or BFBAI 2 -stoichiometry C 14 H 12 F 6 I 2 N 2 ), has been described 4,5 as an improvement of the power conversion efficiency as well as of the device stability. The BFBAI 2 structure and spectra have also been calculated 5 with density-functional theory (DFT), including its dimer (and even evaluating perovskite influence).…”