Structural Flexibility Slows Down Charge Transfers in Diaminoterephthalate-C₆₀ Dyads

Abstract

In recent years, research has emphasized the significant influence of vibronic couplings 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.

Condensed Matter Systems Exposed to Radiation: Multiscale Theory, Simulations, and Experiment

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