Low Bandgap Polymers by Copolymerization of Thiophene with Benzothiadiazole

✍ Scribed by Youjun He; Xiang Wang; Jing Zhang; Yongfang Li

• Book ID: 102491714
• Publisher: John Wiley and Sons
• Year: 2009
• Tongue: English
• Weight: 220 KB
• Volume: 30
• Category: Article
• ISSN: 1022-1336
• DOI: 10.1002/marc.200800507

✦ Synopsis

Abstract

Three low bandgap copolymers of thiophene and benzothiadiazole with electron‐donating and electron‐withdrawing substituents, P1, P2, and P3, have been synthesized by Pd‐catalyzed Stille‐coupling. Electronic energy levels of the polymers are estimated by cyclic voltammetry. The polymer films show a broad absorption band in the wavelength range from 300 to 750 nm. Among the polymers, the polymer that contains the 5,6‐dinitrobenzothiadiazole unit, P3, possesses the smallest bandgap of 1.55 eV calculated from its absorption band‐edge at ≈800 nm. With the increase of the electron‐withdrawing ability of the substituents on the benzothiadiazole unit, the energy bandgap of the polymers decreased in the order P1 > P2 > P3. The results indicate that stronger electron‐withdrawing substituents on the acceptor unit can effectively decrease the bandgap of the polymers.

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