Conjugated block copolymers are potentially useful for organic electronic applications and the study of interfacial charge and energy transfer processes; yet few synthetic methods are available to prepare polymers with well-defined conjugated blocks. Here, we report the synthesis and thin film morphology of a series of conjugated poly(3-hexylthiophene)-block-poly(9,9-dioctylfluorene) (P3HT-b-PF) and poly(3-dodecylthiophene)-block-poly(9,9-dioctylfluorene) (P3DDT-b-PF) block copolymers prepared by functional external initiators and click chemistry. Functional group control is quantified by proton nuclear magnetic resonance spectroscopy, size-exclusion chromatography, and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. The thin film morphology of the resulting all-conjugated block copolymers is analyzed by a combination of grazing-incidence X-ray scattering, atomic force microscopy, and transmission electron microscopy. Crystallization of the P3HT or P3DDT blocks is present in thin films for all materials studied, and P3DDT-b-PF films exhibit significant PF/P3DDT co-crystallization. Processing conditions are found to impact thin film crystallinity and orientation of the - stacking direction of polymer crystallites. (c) 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014, 52, 154-163