We have concluded that no triplet excitons, and therefore no ISC, was detected over the 8 ns TA measurements of 0.05 mM TIPS-Pn and TIPS-Tn. But, there may still be a triplet population that is below the detection limit, that is, some magnitude of triplet excitons that is unresolvable over the time window and at the signal-to-noise ratio present in this study. Given the bimolecular SF rates determined in the previous section, we can estimate the amount of triplet excitons that could be present due to a very small amount of diffusion-limited SF at 0.05 mM, and therefore the amount of triplet excitons that could possibly be present due to ISC.