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Spin-dependent electron-hole capture kinetics in conjugated polymers

Stoyan Karabunarliev·Eric. R. Bittner
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Abstract

The recombination of electron-hole pairs injected in extended conjugated systems is modeled as a multi-pathway vibron-driven relaxation in monoexcited state-space. The computed triplet-to-singlet ratio of exciton formation times $r = τ_T/τ_S$ increases from 0.9 for a model dimer to 2.5 for a 32-unit chain, in excellent agreement with experiments. Therewith we rationalize recombination efficiency in terms of spin-dependent interstate vibronic coupling and spin- and conjugation-length-dependent exciton binding energies.Our model calculations for various length polymers indicate that the ratio of the singlet to triplet formation ratios, $r = σ_S/σ_T$, is inversely related to the ratio of the singlet and triplet binding energies, $ε^b_S/ε^b_T$.

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Stoyan Karabunarliev, Eric. R. Bittner. 2002-07-01. Spin-dependent electron-hole capture kinetics in conjugated polymers. https://doi.org/10.1103/physrevlett.90.057402

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