Influence of Heterocyclic Spacer and End Substitution on Hole Transporting Properties Based on Triphenylamine Derivatives: Theoretical Investigation

Hybrid organic−inorganic halide−perovskite based solar cells have achieved outstanding progress, approaching one of the most competitive photovoltaic technologies. One of the hot topics is to develop inexpensive and efficient hole transporting materials to improve the performance of devices for practical applications. In this paper, we theoretically design a series of hole transporting materials based on triphenylamine backbone through varying the spacer and the end substitution. The properties of frontier molecular orbital, ionization potential, reorganization energy, and charge mobility have been calculated and analyzed. The results show that the spacer and the end functional groups strongly influence the molecular geometry, stacking, electron density distribution, and especially hole mobility. The best hole transporting material with furan as spacer and hydroxyl or methoxyl as substitution is proposed due to its highest hole transporting mobility induced by the planar conformation and tight π−π stacking, which potentially could enable the highly efficient perovskite solar cells.