Axial/Peripheral Halogen‐Substituted Phenoxy Boron Subphthalocyanines for Application as Electron Acceptors Materials for Organic Solar Cells and Hole Transport Materials for Perovskite Solar Cells: A DFT Approach

Abstract Organic photovoltaic cells (OPVs) are a promising low‐cost renewable energy technology. Among various semiconductors studied for OPVs, boron subphthalocyanine chloride (Cl‐BsubPc) is one of the most explored. Phenoxy‐substituted BsubPc (PhO‐subPc) is an analogue of Cl‐BsubPc that introduces an axial phenoxy ligand in order to tune its electronic properties. In this paper, the effects of halogen substitution on the optoelectronic properties of PhO‐subPc are discussed in terms of the nature, number, and location of halogen atoms. DFT calculations show that the peripheral halogen substitutions significantly decrease the exciton binding energy value, increase the reorganization energy value, and also improve the light‐harvesting efficiency of the mentioned molecules. These modifications are symptoms of improved exciton separation and charge transport; hence, the peripherally halogenated PhO‐subPc are those that exhibit the best performances. However, the phenoxy‐substituted BsubPc do not enhance the performance of the boron subphthalocyanine chloride as far as the hole transport materials (HTM) of organic solar cells are concerned.