The resulting kinetic model fits are shown in Fig. , where again the shaded gray region represents the range of possible kinetics that fit the triplet concentration. This model is able to capture the behavior of TIPS-Tn reasonably well. The triplet formation kinetics are reproduced well, and the singlet decay has some small discrepancies, which, as with TIPS-Pn, we attribute to solvent reorganization or the presence of some additional S 1 deactivation pathways. The bimolecular SF rate fits to (2.6 ± 0.6) × 10 9 M -1 s -1 . At 8 mM this value corresponds to a pseudo-first-order rate constant of (2.1 ± 0.5) × 10 7 s -1 , or a time constant of 51±11 ns. The full range of fitted values corresponding to the upper and lower limits of T 1 concentrations are given in Table of the supplementary material. Dover et al. previously fit a pseudo-first-order SF rate constant for TIPS-Tn of 3.18×10 8 s -1 at 300 mM, which is equivalent to a bimolecular SF rate of 1.06×10 9 M -1 s -1 . 15 This value is only slightly lower than the rate constant fit here. However, both Stern et al. ) is due to excimer formation, rather than SF. Only about 3% of singlet excitons undergo SF to form T 1 . Additionally, a maximum T 1 yield of only 1.25% is observed, because most of the triplets formed rapidly undergo triplet fusion. A significant amount of excimer formation is predicted by the Dover model at 8 mM (34%), but, as discussed previously, the TA data fits well to just two components (S 1 and T 1 ) without additional absorption or emission that could be due to excimers. It is possible that the spectral component we assign to T 1 could instead be due to excimers, but, as we show in Fig. of the supplementary material, the spectral shape is consistent with previously assigned T 1 basis spectra. Additionally, the excimer state is emissive, but there is an absence of any obvious emission features in the basis spectrum that correspond to the excimer emission characterized by Dover et al.. Instead, we attribute the discrepancy between the Dover model and the TA data in this study to the concentrations of TIPS-Tn used. Both Dover et al. and Stern et al. used concentrations of 300 mM, 37.5 times higher than the 8 mM samples used here. We observed that agitation is required to dissolve 8 mM solutions of TIPS-Tn in toluene, and therefore propose that at a concentration of 300 mM TIPS-Tn may only be partially soluble, and consequently that aggregation may begin to occur at that concentration.