A strategy for revealing the packing in semicrystalline π-conjugated polymers: crystal structure of bulk poly-3-hexyl-thiophene (P3HT).

To tilt or not to tilt: The crystal structure for bulk P3HT (phase I) was determined by "multi-technique crystallography", which combines X-ray diffraction, solid-state NMR spectroscopy, and DFT calculations. The results showed that this semiconducting polymer crystallizes in the monoclinic space group P2(1)/c with nontilted π-stacks at a distance of 3.9 Å (see picture).