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  • Null Exciton Splitting in C...
    Sebastian, Ebin; Philip, Abbey M.; Benny, Alfy; Hariharan, Mahesh

    Angewandte Chemie International Edition, November 26, 2018, Volume: 57, Issue: 48
    Journal Article

    Exciton interactions in molecular aggregates play a crucial role in tailoring the optical behaviour of π‐conjugated materials. Though vital for optoelectronic applications, ideal Greek cross‐dipole (α=90°) stacking of chromophores remains elusive. We report a novel Greek cross (+) assembly of 1,7‐dibromoperylene‐3,4,9,10‐tetracarboxylic tetrabutylester (PTE‐Br2) which exhibits null exciton coupling mediated monomer‐like optical characteristics in the crystalline state. In contrast, nonzero exciton coupling in X‐type (α=70.2°, PTE‐Br0) and J‐type (α=0°, θ=48.4°, PTE‐Br4) assemblies have perturbed optical properties. Additionally, the semi‐classical Marcus theory of charge‐transfer rates predicts a selective hole transport phenomenon in the orthogonally stacked PTE‐Br2. Precise rotation angle dependent optoelectronic properties in crystalline PTE‐Br2 can have consequences in the rational design of novel π‐conjugated materials for photonic and molecular electronic applications. Monomer‐like aggregates: Null exciton coupling in an ideal Greek cross‐dipole (+) assembly affords monomer‐like optical properties and an exceptional charge‐filtering (selective hole transport) effect in orthogonal chromophore stacks.