Distinct Roles of Subphthalocyanine in the Ultrafast Photodynamics of Three Donor-Acceptor Conjugates Directly Linked by a Single B-N Bond Revealed by Nonadiabatic Dynamics Simulations

Abstract

Herein, we have investigated the photodynamics of three donor-acceptor subphthalocyanine (SubPc) based conjugates, namely SubPc-PDI, PTZ-SubPc, and PTZ-SubPcF, with the combination of the linear-response time-dependent density functional theory (LR-TDDFT) based static electronic structure calculations and nonadiabatic molecular dynamics (NAMD) simulations. Based on the obtained results, the distinct roles of SubPc in different conjugates are confirmed. In SubPc-PDI, the SubPc fragment is acting as an electron donor while in PTZ-SubPc and PTZ-SubPcF, it behaves as an electron acceptor. As a result, the photodynamics of these conjugates also varies upon excitation around the lowest absorption band of SubPc. For SubPc-PDI, the energy transfer from SubPc to PDI takes place ultrafast within 500 fs. In contrast, the hole transfer from SubPc/SubPcF is observed in the PTZ-SubPc/SubPcF conjugates. Moreover, the fluorine substitution can significantly lower the energy of charge transfer states in the PTZ-SubPc based conjugates, leading to more efficient charge transfer extent. Our present work not only agrees well with previous experimental study, but also provides more details on the photoinduced dynamics of SubPc-based donor-acceptor systems. Moreover, the employed methods in this work turn out to be efficient for exploring the photodynamics of these systems, which can be helpful for the elucidation of complicated photodynamics in various organic donor-acceptor systems.

Keywords: subphthalocyanine, donor-acceptor conjugates, nonadiabatic dynamics simulations, photoinduced electron transfer, photoinduced energy transfer