Null Exciton Splitting in Chromophoric Greek Cross?(+) Aggregate

摘要： Exciton interactions in molecular aggregates play a crucial role in tailoring the optical behaviour of p-conjugated materials. Though vital for optoelectronic applications, ideal Greek cross-dipole (a = 908) 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 (a = 70.28, PTE-Br0) and J-type (a = 08, q = 48.48, 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 p-conjugated materials for photonic and molecular electronic applications.