Improved Photovoltaic Performance of a Semicrystalline Narrow Bandgap Copolymer Based on 4H-Cyclopenta[2,1-b:3,4-b鈥瞉dithiophene Donor and Thiazolo[5,4-d]thiazole Acceptor U

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• 作者：Sarah Van Mierloo ; Afshin Hadipour ; Mark-Jan Spijkman ; Niko Van den Brande ; Bart Ruttens ; Jurgen Kesters ; Jan D鈥橦aen ; Guy Van Assche ; Dago M. de Leeuw ; Tom Aernouts ; Jean Manca ; Laurence Lutsen ; Dirk J. Vanderzande ; Wouter Maes
• 刊名：Chemistry of Materials
• 出版年：2012
• 出版时间：February 14, 2012
• 年：2012
• 卷：24
• 期：3
• 页码：587-593
• 全文大小：383K
• 年卷期：v.24,no.3(February 14, 2012)
• ISSN：1520-5002

文摘

A solution processable narrow bandgap polymer composed of alternating 2,5-dithienylthiazolo[5,4-d]thiazole and asymmetrically alkyl-substituted 4H-cyclopenta[2,1-b:3,4-b鈥瞉dithiophene units (PCPDT-DTTzTz) was synthesized by Suzuki polycondensation and the donor鈥揳cceptor copolymer was thoroughly characterized. Thermal analysis and X-ray diffraction studies disclosed the semicrystalline nature of the material. When blended with PC₇₁BM and integrated in bulk heterojunction organic solar cells, a moderate power conversion efficiency of 2.43% under AM 1.5 G (100 mW/cm²) conditions was obtained. However, upon purification of the semiconducting copolymer by preparative size exclusion chromatography, a noticeable rise in power conversion efficiency to 4.03% was achieved. The purified polymer exhibited a relatively high field-effect carrier mobility of 1.0 脳 10^鈥? cm²/(V s). The active layer morphology was explored by atomic force microscopy and transmission electron microscopy studies, showing phase segregation on the nanometer scale.

Keywords:

4H-cyclopenta[2,1-b:3,4-b鈥瞉dithiophene; thiazolo[5,4-d]thiazole; alkyl side chains; semicrystallinity; preparative GPC; bulk heterojunction organic solar cells