Microstructural model of Indacenodithiophene-co-benzothiadiazole Polymer: π-crossing interactions and their potential impact on charge transport

Morphological and electronic properties of Indacenodithiophene-co-benzothiadiazole (IDTBT) co-polymer with varying molecular weights are calculated through combined molecular dynamics (MD) and quantum chemical (QC) methods. Our study focuses on the polymer chain arrangements, interchain connectivity pathways, and interplay between morphological and electronic structure properties of IDTBT. Our models, which are verified against X-ray scattering measurements, show a considerable number of BT-BT π-π interactions with a (preferential) perpendicular local orientation of polymer chains due to the steric hinderance of bulky sidechains around IDT. The BT-BT (interchain) crossing points show some degree of order in spatial arrangement which most likely result in a mesh-like structure for the polymer and provide efficient pathways for interchain charge transport.