The spectra of the reference sample are shown in Fig. 3(a) for different pump-probe delays. As previously observed on , there are six salient features in the visible spectral range:28 three photobleaching peaks of the exciton absorption resonances , , and , and three photoinduced absorption peaks , , and ascribed to photogenerated charges, one for each of the excitons. The exciton bleaching features show a fast decay during the first few picoseconds, followed by a slower decay on the few-100 ps scale. The photoinduced absorption peaks grow during the first few picoseconds and then decay with a characteristic time similar to the slow exciton decay. Charge photogeneration occurs via a combination of a direct excitation mechanism (i.e., within our instrumental resolution of ), and via dissociation of hot excitons, on a time scale of a few hundred femtoseconds to few picoseconds.28 This process can be seen in Fig. 3(a) as a fast decrease of the bleaching features , , and and a corresponding growth of the charge features , , and during the first few picoseconds. Together with the spectral change of shape—relative increase of the absorption and decrease of the bleaching features—the peaks also undergo a blueshift with increasing delay. In a more comprehensive study with different excitation fluences, it was found that the more the excited states the more the spectra are shifted to the red.28 This has been explained as Stark effect due to photoexcited charges,16,29 inter-excitonic interaction,30 or band gap renormalization.31 Additionally, at short delays, the and photoinduced absorption peaks appear artificially redshifted due to the strong overlap with the and bleaching peaks, respectively. The fast decay of the bleaching peaks diminishes this effect with increasing pump-probe delay, resulting in an additional apparent temporal blueshift of these two photoinduced absorption features. After , there is no significant shift of the spectra anymore and all features decay with a time constant of several hundred picoseconds, as has already been observed14 on individual flakes of . Comparing the reference sample with those of different SC [Figs. 3(b) and 3(c)], one finds a trend toward slightly faster decay for higher SC. Additionally, for higher SC, the C exciton bleaching is weaker.