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arXiv · 1508.00071

Theory of Primary Photoexcitations in Donor-Acceptor Copolymers

Karan Aryanpour·Tirthankar Dutta·Uyen N. V. Huynh·Zeev Valy Vardeny·Sumit Mazumdar
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Abstract

We present a generic theory of primary photoexcitations in low band gap donor-acceptor conjugated copolymers. Because of the combined effects of strong electron correlations and broken symmetry, there is considerable mixing between a charge-transfer exciton and an energetically proximate triplet-triplet state with an overall spin singlet. The triplet-triplet state, optically forbidden in homopolymers, is allowed in donor-acceptor copolymers. For an intermediate difference in electron affinities of the donor and the acceptor, the triplet-triplet state can have stronger oscillator strength than the charge-transfer exciton. We discuss the possibility of intramolecular singlet fission from the triplet-triplet state, and how such fission can be detected experimentally.

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Karan Aryanpour, Tirthankar Dutta, Uyen N. V. Huynh, Zeev Valy Vardeny, Sumit Mazumdar. 2015-12-31. Theory of Primary Photoexcitations in Donor-Acceptor Copolymers. https://doi.org/10.1103/physrevlett.115.267401

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