Addressing the challenge of designing efficient organic photovoltaics requires a detailed understanding of both the low-lying electronic excited states of molecular systems and the coupled nuclear-electron dynamics that drive exciton diffusion and dissociation. In the first part of this talk, we focus on our work towards developing novel path integral based methods for approximate quantum dynamics that employ only classical trajectories to simulate condensed phase charge transfer reactions. In the second part, we turn our attention to Singlet Fission (SF), a phenomenon that may hold the key to increasing the efficiency of organic solar cells. In SF, a singlet exciton formed by photon absorption spontaneously splits to form to two longer-lived triplet excitons that can, in turn, dissociate to generate two free charges for every photon absorbed. Using accurate electronic structure to characterize excited states and normal mode analysis to identify important molecular vibrational modes, we uncover two distinct mechanistic pathways for ultrafast SF in pentacene-based materials and we discuss the implications for materials design.

Charge transfer dynamics, excited state energetics, and organic photovoltaics

253rd National Meeting (2017)

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