Figure 5.

Regimes of triplet–triplet annihilation in aggregate II. (a) Integrated decay kinetics of II following sub-ps excitation at 2.6 eV. The same multiexponential function fits the decay at all fluences, requiring the recombination process to be entirely geminate. Lifetimes (0.9, 6, and 49 ps) are not assigned to individual processes but rather reflect the wide distribution of triplet pair decay rates. (b) Integrated decay kinetics of II on longer time scales, following ns excitation at 2.3 eV, show strong fluence dependence indicative of non-geminate TTA.