Polythiophene-block-polyfluorene and Polythiophene-block-poly(fluorene-co-benzothiadiazole): Insights into the Self-Assembly of All-Conjugated Block Copolymers

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• 作者：Rafael Verduzco ; Ioan Botiz ; Deanna L. Pickel ; S. Michael Kilbey ; II ; Kunlun Hong ; Elaine Dimasi ; Seth B. Darling
• 刊名：Macromolecules
• 出版年：2011
• 出版时间：February 8, 2011
• 年：2011
• 卷：44
• 期：3
• 页码：530-539
• 全文大小：1110K
• 年卷期：v.44,no.3(February 8, 2011)
• ISSN：1520-5835

文摘

All-conjugated block copolymers have significant potential for solution-processed optoelectronic applications, in particular those relying on a p/n junction. Herein, we report the synthesis and structure of all-conjugated diblock copolymers poly(3-hexylthiophene)-block-poly(9,9-dioctylfluorene) and poly(3-hexylthiophene)-block-poly(9,9-dioctylfluorene-co-benzothiadiazole) in thin films and in the bulk. The diblock copolymers are prepared using a combination of Grignard metathesis polymerization and Suzuki polycondensation and characterized with NMR spectroscopy, size-exclusion chromatography, multiangle laser light scattering, and UV/vis spectroscopy. Structure in thin films and in the bulk is characterized using differential scanning calorimetry, X-ray diffraction, small-angle X-ray scattering, and atomic force microscopy. Diblock copolymer thin films self-assemble into a crystalline nanostructure with some long-range order after extended solvent annealing, and X-ray scattering measurements show that powder samples exhibit crystallinity throughout the bulk. By temperature dependent X-ray scattering measurements, we find that diblock copolymers self-assemble into crystalline nanowires with phase segregated block copolymer domains. These measurements show all-conjugated diblock copolymers may be useful for achieving solution-processed active layers in organic photovoltaics and light-emitting diodes with optimized structural and photophysical characteristics.