TY - JOUR AU - Aster, A. AU - Zinna, F. AU - Rumble, C. AU - Lacour, J. AU - Vauthey, E. TI - Singlet Fission in a Flexible Bichromophore with Structural and Dynamic Control PY - 2021 JF - Journal of the American Chemical Society JA - J. Am. Chem. Soc. SN - 0002-7863 VL - 143 SP - 2361 EP - 2371 L1 - https://pubs.acs.org/doi/pdf/10.1021/jacs.0c12384 L2 - https://doi.org/10.1021/jacs.0c12384 L3 - https://doi.org/10.1021/jacs.0c12384 L4 - http://www.unige.ch/sciences/chifi/publis/pics/double/ref01660.png M3 - 10.1021/jacs.0c12384 UR - http://dx.doi.org/10.1021/jacs.0c12384 N2 - Singlet fission (SF), i.e., the splitting of a high-energy exciton into two lower-energy triplet excitons, has the potential to increase the efficiency for harvesting spectrally broad light. The path from the photopopulated singlet state to free triplets is complicated by competing processes that decrease the overall SF efficiency. A detailed understanding of the whole cascade and the nature of the photoexcited singlet state is still a major challenge. Here, we introduce a pentacene dimer with a flexible crown ether spacer enabling a control of the interchromophore coupling upon solvent-induced self-aggregation as well as cation binding. The systematic change of solvent polarity and viscosity and excitation wavelength, as well as the available conformational phase space, allows us to draw a coherent picture of the whole SF cascade from the femtosecond to microsecond time scales. High coupling leads to ultrafast SF ( ID - 1660 ER -