Modern solar cell technologies may be made more economical by harnessing new physical phenomena and materials, thus enabling the production of highly efficient and mechanically flexible organic solar cells on a large scale. Singlet fission (SF) has the potential to increase solar cell efficiency by 30% by converting a single exciton generated by photon absorption into two charge carriers. There are two distinct types of SF systems: intermolecular SF, which produces an exciton on each of two neighboring molecules; and intramolecular SF, which produces both excitons on a single molecule. Although single-molecule SF systems are highly sought after due to their increased applicability in many types of solar cells, they have lower conversion efficiencies than intermolecular systems. Recent experimental studies on quinoidal bithiophenes have suggested intramolecular SF activity with an exciton yield of 170%. The underlying mechanism for this process has yet to be characterized in detail by theoretical methods. In this talk, simulations of the coupling between electronic and nuclear degrees of freedom in these molecules will be presented, including high-level CASPT2 and spin-flip electronic structure calculations.

Theoretical investigation of singlet fission in quinoidal bithiophenes

249th National Meeting (2015)

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