We are examining new dye molecules, which undergo singlet fission (SF), using guidance from electronic structure calculations to assure the requisite relationships between molecular singlet and triplet energy levels. We are preparing hierarchical assemblies from these chromophores, starting from covalent dimers and trimers, then developing supramolecular assemblies, and engineered crystalline materials to investigate SF in bulk, ordered materials. We are using femtosecond transient absorption, emission, stimulated Raman, and infrared spectroscopy as well as time-resolved electron paramagnetic resonance spectroscopy to characterize the SF mechanism and the factors that determine its efficiency at time scales down to 100 fs. We are also using X-ray diffraction to investigate the single crystal structures of these materials and X-ray scattering on their thin polycrystalline solid films to determine how their structures correlate with their ability to carry out SF. Our preliminary results suggest that the p-p slip-stacked geometry is important for maximizing SF efficiency.

Excited state dynamics and structural investigations of singlet fission in molecular solids

244th National Meeting (2012)

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