Subpicosecond photoinduced Stark spectroscopy in fullerene-based devices

We present a detailed study of the charge photogeneration and decay kinetics in [6,6]-phenyl C61-butyric acid methyl ester by performing subpicosecond Stark spectroscopy measurements. Owing to the large photogenerated charge density and the strength of the applied field, progressive quenching of the Stark signal is observed during the first 20 ps, followed by a slow recovery at longer time scales. The quenching regime provides information on the average e-h separation and drift motion within the e-h pair whereas the recovery is related to the kinetics of charges and their recombination probability.