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

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, , modified with two C units in the donor indacenodithiophene. Exciting the C 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 times longer than that of the s-ET products. These attributes endow 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.