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 π-interaction of the frontier layers of regioregular poly(3-hexylthiophene) 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.