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

摘要: The orientation and packing of semiconducting polymer chains at film interfaces crucially affects charge injection transport those interfaces. Although X-ray diffraction techniques have been used extensively as a structural probe, they are not particularly sensitive to these Near-edge absorption fine-structure spectroscopy (NEXAFS), on the other hand, is surface has applied investigate structures, for example, in polyimide, [1] polyfluorene, [2] polythiophene. [3] Here we show that NEXAFS band shapes intensities fact also intermolecular p-interaction regioregular poly(3-hexylthiophene) (rreg-P3HT) films. spectra same material deposited from different solvents processing conditions substantially different. This indicates far more extensive breakdown “building-block” picture than previously reported, [4,5] allowing p-interactions be studied. sensitivity recently established ca. 2.5 nm total electron yield rregP3HT, [6] which highly relevant interfacial surface-induced self-organization. Rreg-P3HT thin films were wide range solvent qualities, both air substrate Delamination was expose interface. We found that: i) thiophene (Th)-ring disordered showed only weak preference out-of-plane (oop) stacking favorable field-effect mobility (lFET); ii) hexyl side disordered; iii) interchain strongly dependent deposition quality, varied opposite directions between interfaces, being generally better Direct imaging by friction-mode atomic force microscopy (AFM) revealed expected presence mosaic morphology with finer length scale topography. Transistor lFET measurements suggested high lFETof rreg-P3HT still limited heterogeneity, attribute distribution interface domains varying and/or packing. ability directly measure chain segmental interaction will open way their systematic optimization even higher device performance. self-organization behavior polymers significant scientific technological interest. Much knowledge conjugated such prototype high-lFET polymer, come