Solvent effects on chain orientation and interchain π-interaction in conjugated polymer thin films:: Direct measurements of the air and substrate interfaces by near-edge X-ray absorption spectroscopy

The orientation and pi-interaction of the frontier layers of regioregular poly(3-hexyl-thiophene) at both the air and substrate interfaces are directly measured for the first time using near-edge X-ray absorption fine-structure spectroscopy for thin films cast from a series of solvents (see figure). Results suggest the already high hole mobility in this material is still substantially limited by disorder at the interfaces.