Remarkable enhancement of ambient-air electrical conductivity of the perylenediimide π-stacks isolated in the flexible films of a hydrogen-bonded polymer

Abstract

N,N′-di(2-(trimethylammoniumiodide)ethylene) perylenediimide (TAIPDI), forming extensive π-stacks through the strong π–π interactions of large π-planes, was isolated in the hydrogen-bonding milieu of polyvinyl alcohol (PVA) from aqueous solutions. The stacking behaviour of TAIPDIs in PVA films was investigated by using UV-vis and magic angle spinning nuclear magnetic resonance (MAS NMR) spectroscopy. It was concluded that the TAIPDI molecules were organized as extensive π-stacks in the PVA matrix controlled by the interactions with the polymer chains. The resulting films of TAIPDI/PVA were doped with electrons by using a strong reducing agent. The electrical current obtained in the electron-doped TAIPDI/PVA films was 740 times higher under the same bias as compared to that of reduced TAIPDIs cast on a glass substrate without a polymer additive. The significant increase in the conductivity of electron-doped TAIPDI/PVA films reflects the strong effect of the uninterrupted π-stacking of TAIPDIs extending in the flexible PVA films and the protection of the doped electrons from the oxygen in the air, provided by the H-bonded environment in PVA.