Structural Flexibility Slows Down Charge Transfers in Diaminoterephthalate-C60 Dyads
Daniel Timmer, Germann Hergert, Luca Gerhards, Daniel C. Lünemann, Nils Schröder, Tobias Greven, Jarl Ivar van der Vlugt, Antonietta De Sio, Ilia A. Solov'yov, Jens Christoffers, Christoph Lienau
Journal of Physical Chemistry C
In recent years, research has emphasized the significant influence of vibroniccouplings on charge separation in donor-acceptor molecules and thin films. Diaminoterephthalates (DATs), known for their versatile optical and electronic properties, are intriguing donor materials. Efficient, vibronically assisted charge separation in DAT-acceptor dyads has been suggested. This study therefore investigates charge separation dynamics in DAT-linker-fullerene dyads in a polar solvent by using transient absorption spectroscopy. The results demonstrate photoinduced electron transfers with close to unity efficiency, occurring within 10-80 ps for benzene and biphenyl linkers. Surprisingly, there is a lack of orientational alignment between the donor and acceptor units indicating a notable conformational flexibility that hinders electron transfer. Time-dependent density functional calculations support this finding. The obtained insights are crucial for developing and comprehending charge-transfer dyads under strong vibronic coupling conditions.