Photoinduced ultrafast multielectron transfer and long-lived charge-accumulated state in a fullerene-indacenodithiophene dumbbell triad.

Wang, Chong; Wu, Bo; Li, Yang; Jiang, Ying; Dong, Tianyang; Zhou, Shen; Wang, Chunru; Bai, Chunli · Proc Natl Acad Sci U S A · 2024

basic_science · Level V

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Abstract

Photoinduced ultrafast multielectron transfer (m-ET) and long-lived charge-accumulated states in single molecules hold promise for light-energy conversion and utilization. However, compared to single-electron transfer (s-ET), m-ET tends to be thermodynamically and kinetically unfavorable. Here, we construct a dumbbell-shaped fullerene-indacenodithiophene triad, <b>IT2</b>, modified with two C<sub>60</sub> units in the donor indacenodithiophene. Exciting the C<sub>60</sub> units, ultrafast m-ET occurs with a time constant of 0.5 ps, accumulating two holes with a lifetime of 10 μs. Benefitting from a larger driving force, lower reorganization energy, and smaller structural changes, the rate of m-ET is 23 times faster than that of s-ET, and the lifetime of the m-ET product is 1.4 × 10<sup>5</sup> times longer than that of the s-ET products. These attributes endow <b>IT2</b> with superior photocatalytic performance in multielectron oxidation reactions. This is an instance of achieving faster m-ET and a longer m-ET product lifetime than s-ET in a single molecule. This finding provides unique insights for the construction and application of intramolecular m-ET and charge accumulation systems in photocatalysis and molecular devices.