Conjugated Polymers Based on a New Building Block: Dithienophthalimide

• Published in: Macromolecules Vol. 44; no. 11; pp. 4213 - 4221
• Main Authors: Wang, Haifeng, Shi, Qinqin, Lin, Yuze, Fan, Haijun, Cheng, Pei, Zhan, Xiaowei, Li, Yongfang, Zhu, Daoben
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 14.06.2011
• Subjects: Applied sciences; Energy; Exact sciences and technology; Natural energy; Organic polymers; Photovoltaic conversion; Physicochemistry of polymers; Polymers with particular properties; Preparation, kinetics, thermodynamics, mechanism and catalysts; Solar cells. Photoelectrochemical cells; Solar energy; Terpolymer; Photoluminescence; Aromatic polymer; Organic solar cells; Fill factor; Thermal stability; Imide; Conjugated polymer; Thiazole derivative copolymer; Thiophene derivative polymer; Optical properties; Nitrogen heterocycle copolymer; Aromatic copolymer; Thiophene derivative copolymer; Optical absorption; Stille coupling; Short circuit currents; Solution polycondensation; Thiophene copolymer; Experimental study; Open circuit voltage; Suzuki coupling; Nitrogen heterocycle polymer; Electrochemical properties; Conjugated copolymer; Preparation; Soluble compound
• ISSN: 0024-9297; 1520-5835
• DOI: 10.1021/ma2003097

A new fused-ring building block dithieno[3,2-f:2′,3′-h]phthalimide was synthesized and used in synthesis of conjugated polymers. On the basis of this building block, we designed and synthesized a series of conjugated copolymers containing electron-rich unit benzo[1,2-b:4,5-b′]dithiophene (P1 and P2) or with electron-deficient unit 2,2′-bithiazole (P3 and P4) or benzo[c][1,2,5]thiadiazole (P5) and homopolymer (P6). P1 and P4–P6 have good solubility in common organic solvents, while P2 and P3 have poor solubility. P1–P6 exhibit good thermal stability with 5% weight loss temperatures of 193–417 °C. P1–P6 in films exhibit absorption maxima of 482–532 nm with optical bandgaps of 1.88–2.25 eV and weak emission peaked at 597–721 nm. P1–P6 have estimated HOMOs of −5.3 to −6.2 eV and LUMOs of −2.8 to −3.4 eV. The optical properties and HOMO/LUMO levels are influenced by the comonomers. The polymer solar cells based on P1:PC61BM (1:1, w/w) exhibit preliminary power conversion efficiency of 0.30% under an AM 1.5 simulated solar light at 100 mW/cm2.