Oriented blend films of poly(3-hexylthiophene) and [6,6]-phenyl-C61-butyric acid methyl ester fabricated by friction transfer method

We have been studying oriented thin films of polymers fabricated by the friction transfer method, which allows a variety of conjugated polymers to be aligned into highly oriented films. However, with this method it is difficult to prepare oriented films from a mixture. In this work we prepared oriented thin films of a mixture of regioregular poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl-C-61-butyric acid methyl ester (PCBM), which is a promising combination for application in organic solar cells. We obtained oriented blend films of P3HT and PCBM by the friction transfer method from a solid block prepared from a mixed solution with a weight ratio of 1 : 1. Atomic force microscopy shows that microscale phase separation took place in the blend films. Polarized UV-visible spectra show that the P3HT chains were aligned parallel to the friction direction in the blend films. X-ray diffraction studies suggested that the preferred orientation of P3HT crystallites was the face-on orientation in the blend film. (C) 2014 The Japan Society of Applied Physics