Theory of exciton transfer and diffusion in conjugated polymers
We describe a theory of Förstertype exciton transfer between conjugated polymers. The theory is built on three assumptions. First, we assume that the lowlying excited states of conjugated polymers are Frenkel excitons coupled to local normal modes, and described by the FrenkelHolstein model. Second, we assume that the relevant parameter regime is ℏω < J, i.e., the adiabatic regime, and thus the BornOppenheimer factorization of the electronic and nuclear degrees of freedom is generally applicable. Finally, we assume that the Condon approximation is valid, i.e., the excitonpolaron wavefunction is essentially independent of the normal modes. The resulting expression for the exciton transfer rate has a familiar form, being a function of the exciton transfer integral and the effective FranckCondon factors. The effective FranckCondon factors are functions of the effective HuangRhys parameters, which are inversely proportional to the chromophore size. The BornOppenheimer expressions were checked against DMRG calculations, and are found to be within 10% of the exact value for a tiny fraction of the computational cost. This theory of exciton transfer is then applied to model exciton migration in conformationally disordered poly(pphenylene vinylene). Key to this modeling is the assumption that the donor and acceptor chromophores are defined by localmore »
 Authors:

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 Department of Chemistry, Physical and Theoretical Chemistry Laboratory, University of Oxford, Oxford OX1 3QZ (United Kingdom)
 (United Kingdom)
 Publication Date:
 OSTI Identifier:
 22310723
 Resource Type:
 Journal Article
 Resource Relation:
 Journal Name: Journal of Chemical Physics; Journal Volume: 141; Journal Issue: 16; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
 Country of Publication:
 United States
 Language:
 English
 Subject:
 37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; BORNOPPENHEIMER APPROXIMATION; CENTEROFMASS SYSTEM; COMPUTERIZED SIMULATION; DEGREES OF FREEDOM; DIFFUSION; DIFFUSION LENGTH; EMISSION; EXCITATION; EXCITED STATES; EXCITONS; FACTORIZATION; GROUND STATES; MONTE CARLO METHOD; PEAKS; POLYMERS; SPECTRA; WAVE FUNCTIONS