GW/BSE Nonadiabatic Dynamics Simulations on Excited-State Relaxation Processes of Zinc Phthalocyanine-Fullerene Dyads: Roles of Bridging Chemical Bonds

In this work, we employ electronic structure calculations and nonadiabatic dynamics simulations based on many-body Green function and Bethe-Salpeter equation (GW/BSE) methods to study excited-state properties of a zinc phthalocyanine-fullerene (ZnPc-C _60 ) dyad with 6-6 and 5-6 configurations. In the former, the initially populated locally excited (LE) state of ZnPc is the lowest S _1 state and thus, its subsequent charge separation is relatively slow. In contrast, in the latter, the S _1 state is the LE state of C _60 while the LE state of ZnPc is much higher in energy. There also exist several charge-transfer (CT) states between the LE states of ZnPc and C _60 . Thus, one can see apparent charge separation dynamics during excited-state relaxation dynamics from the LE state of ZnPc to that of C _60 . These points are verified in dynamics simulations. In the first 200 fs, there is a rapid excitation energy transfer from ZnPc to C _60 , followed by an ultrafast charge separation to form a CT intermediate state. This process is mainly driven by hole transfer from C _60 to ZnPc. The present work demonstrates that different bonding patterns (i.e. 5-6 and 6-6) of the C - N linker can be used to tune excited-state properties and thereto optoelectronic properties of covalently bonded ZnPc-C _60 dyads. Methodologically, it is proven that combined GW/BSE nonadiabatic dynamics method is a practical and reliable tool for exploring photoinduced dynamics of nonperiodic dyads, organometallic molecules, quantum dots, nanoclusters, etc.