A regioregular poly4′‐dodecyl‐3‐(1H,1H,2H,2H‐perfluorooctyl)‐2,2′‐bithiophene] (P3DDFT) with alternating alkyl and semifluoroalkyl side chains were synthesized. Short ethylene spacer between perfluorohexyl part and thiophene did not largely affect the absorption and emission properties of the polythiophene backbone in comparison with poly(3‐dodecylthiophene) (P3DDT). P3DDFT showed a larger onset of the oxidation potential (+0.17 V) observed by cyclic voltamogram due to the electron withdrawing effect of the fluoroalkyl part. Thermal analysis and X‐ray diffraction patterns indicated that P3DDFT in the solid state forms a semicrystalline lamellar structure that is similar to that of P3DDT. Ultraviolet photoemission spectroscopy was also used to investigate their electron structure in the films. Comparison of hole mobilities in the films suggested that P3DDFT could have a less ordered packing structure compared to P3DDT both in the bulk and at the dielectric interface.
