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Terminal Modulation in Search of a Balance between Hole Transport and Electron Transfer at the Interface for BODIPY-Based Organic Solar Cells

Zhao, Zhi-Wen, Pan, Qing-Qing, Duan, Ying-Chen, Wu, Yong, Geng, Yun, Wu, Shui-Xing, Su, Zhong-Min
Journal of physical chemistry 2019 v.123 no.11 pp. 6407-6415
absorption, crystal structure, electron transfer, fluorescence, fullerene, geometry, molecular dynamics, quantum mechanics, simulation models, solar cells, solar energy
Organic solar cells (OSCs) have made rapid advances in power conversion efficiency during the past decades, which is boosted partly by the various designs of new materials, especially in donor materials. However, as one kind of famous fluorescence materials, 4,4′-difluoro-4-bora-3a,4a-diaza-s-indacenes (BODIPY)-based materials are seldom applied in OSCs until its conjugated molecules have been synthesized and designed as donors recently. Here, we designed a series of BODIPY molecules by terminal modulation based on a reported one and probed their potential promising properties for donor materials in OSCs by means of quantum chemical calculations and molecular dynamics simulations. Many important parameters pertaining to short circuit density (JSC) such as capability of light absorption, dipole moment transition between the ground and excited states, hole mobility evaluated on the basis of predicted crystal structures, charge-transfer rate (kᵢₙₜₑᵣ₋CT), and charge recombination rate (kᵢₙₜₑᵣ₋CR) computed based on local interface geometries of donor/fullerene selected from molecular dynamics simulation results except for some elemental properties were investigated in detail from a theoretical perspective. The results reveal that the terminal modulation through increasing π-conjugation length is feasible. Notably, it is beneficial to balance the ability of hole transport and charge transfer when considering the π-conjugation length and planarity of donor materials. Finally, we hope that this work can pave the way to the design of potential near-infrared donor materials.