10.1021/jz402450m.s001 Hajime Yamagata Hajime Yamagata Frank C. Spano Frank C. Spano Strong Photophysical Similarities between Conjugated Polymers and J‑aggregates American Chemical Society 2015 radiative decay rates exciton band curvature radiative decay rate excitonic band structure vibronic signatures systems share gamma point square root Strong Photophysical Similarities CP Conjugated Polymers photophysical resemblance band gap semiconductors 2015-12-17 00:28:50 Journal contribution https://acs.figshare.com/articles/journal_contribution/Strong_Photophysical_Similarities_between_Conjugated_Polymers_and_J_aggregates/2028396 The photophysical properties of emissive conjugated polymer (CP) chains are compared to those of linear J-aggregates. The two systems share many properties in common, including a red-shifted absorption spectrum with increasing chain/aggregate length, enhanced radiative decay rates (superradiance) relative to a single monomer/molecule, and several vibronic signatures involving the vinyl-stretching mode common to many conjugated molecules. In particular, the scaling of the 0–0/0–1 photoluminescence ratio and radiative decay rate with the inverse square root of temperature in red-phase polydiacetylene is also characteristic of linear, disorder-free J-aggregates. The strong photophysical resemblance is traced to the excitonic band structure; in one-dimensional direct band gap semiconductors as well as J-aggregates, the exciton band curvature is positive at the gamma point (<i>k</i> = 0).