Fig. 6

Singlet fission time constants and proposed model. a Comparison of experimental results (decay times of the singlet PA extracted at 607 nm in PEN:DIP and build-up times of the triplet PA extracted at 875 nm in PEN:DIP and PEN:PIC, respectively) with the calculated SF rate based on the model discussed. The upper panel shows the experimental time constants in the lower panel with an expanded scale. The error bars indicate the uncertainty of the fit. The results of the calculations have been scaled by 1.38 to match the experimentally determined SF time constant of pure PEN. Deviations between model and experiment are discussed in the text. b A schematic sketch of the potential origin of the deviations of the experimental results from the theoretical predictions showing the two extreme cases of PEN with and without PEN nearest neighbors