Distance Dependence of Triplet Energy Transfer in Water and Organic Solvents: A QM/MD Study

TitleDistance Dependence of Triplet Energy Transfer in Water and Organic Solvents: A QM/MD Study
Publication TypeJournal Article
Year of Publication2012
AuthorsCurutchet, C, Voityuk AA
JournalJournal of Physical Chemistry C
Pagination22179 - 22185
Date Published2012
ISBN Number1932-7447
Keywordselectron-transfer, excitation transfer, exciton resonance interactions, perylene imides, rate expressions, state, systems, up-conversion
AbstractThe possibility to optimize optoelectronic devices, such as organic light-emitting diodes or solar cells, by exploiting the special characteristics of triplet electronic states and their migration ability is attracting increased attention. In this study, we analyze how an intervening solvent modifies the distance dependence of triplet electronic energy transfer (TEET) processes by combining molecular dynamics simulations with quantum chemical calculations of the transfer matrix elements using the Fragment Excitation Difference (FED) method. We determine the beta parameter characterizing the exponential distance decay of TEET rates in a stacked perylene dimer in water, chloroform, and benzene solutions. Our results indicate that the solvent dependence of beta (beta(vaccum) = 5.14 angstrom(-1) > beta(watar) = 3.77 angstrom(-1) > beta(chloroform) = 3.61 angstrom(-1) > beta(benzene) = 3.44 angstrom(-1)) can be rationalized adopting the McConnell model of superexchange, where smaller triplet energy differences between the donor and the solvent lead to smaller beta constants. We also estimate the decay of hole transfer (HT) and excess electron transfer (EET) processes in the system using the Fragment Charge Difference (FCD) method and find that beta(TEET) can be reasonably well approximated by the sum of beta(EET) and beta(HT) constants.