Size effects in triplet-triplet annihilation: II. Monte carlo simulations

The dynamics of triplet-triplet annihilation (TTA) is theoretically studied in linear chains and nanoparticles, modeled as 1D, 2D, and 3D regular lattices, as a function of size M, of the rate of excitation migration W, and of the rate of excitation annihilation V in the diffusion-influenced limit (V ≫ W). It is shown that a sum of two exponentials is usually sufficient for fitting experimental phosphorescence and triplet-triplet absorption decays. The first term describes the decay of domains containing initially one triplet, while the second one reflects the disappearance of domains containing initially two triplets. Monte Carlo calculations were carried out to compute the survival probability of an annihilating pair of triplets, yielding expressions for the dependence of the rate constant of TTA on the parameters M, W, and V in one, two, and three dimensions. The text was submitted by the authors in English.