A hydrogen bonded azine as a building block for π-conjugated polymers and their semiconducting properties†
Abstract
An intramolecular hydrogen bonded azine has been investigated as a building block for π-conjugated polymers. X-ray single crystal diffraction revealed that the azine had a centrosymmetric structure with an E,E configuration of two CN double bonds, and an s-trans conformation in the solid state. The intramolecular hydrogen bonding enabled a rigid coplanar structure, enhanced π-electron delocalization and promoted intermolecular stacking. Two conjugated polymers P1 and P2 based on the new building block were synthesized by Stille cross-coupling reactions. P1 was used as a donor in organic solar cells and the devices showed significant improvement in power conversion efficiency compared to other polyazine based solar cell devices. The semiconducting properties of P2 were evaluated in organic field-effect transistor devices.