D–A conjugated polymers based on thieno[3, 2-b]indole (TI) and 2, 1, 3-benzodiathiazole (BT) derivatives: synthesis, characterization and side-chain influence on photovoltaic properties. Issue 51 (10th May 2016)

• Record Type: Journal Article
• Authors: Huang, Hongyan; Li, Quan; Qiu, Meng; Wang, Zheng; Zhang, Xinzhen; Liu, Shuli; Fu, Nina; Zhao, Baomin; Yang, Renqiang; Huang, Wei
• Is Part Of: RSC advances. Volume 6:Issue 51(2016)
• Page Start: 45873
• Page End: 45883
• Publication Date: 2016-05-10
• Subjects: Chemistry -- Periodicals; 540.5
• DOI: 10.1039/c6ra05413g
• Languages: English
• ISSNs: 2046-2069

Abstract

Abstract : Thieno[3, 2- b ]indole (TI) derivatives were developed via Cadogan annulation for constructing D–A copolymers. Their performance in photovoltaic cells were finely tuned by side-chain engineering. Abstract : A facile synthetic strategy toward thieno[3, 2- b ]indole (TI) derivatives was developed by the Cadogan annulation method. Three donor–acceptor (D–A) conjugated polymersP1, P2 andP3 containing N -alkyl-TI derivatives and 4, 7-dithien-5-yl-2, 1, 3-benzodiathiazole (DTBT) derivatives were successfully synthesized and applied to bulk heterojunction (BHJ) polymer solar cells (PSCs). Different side chains were introduced to TI units (forP2 ) or DTBT units (forP3 ), the results indicate that the bandgaps, energy levels and photovoltaic performance were finely tuned by the side chains in the TI-DTBT copolymer. Power conversion efficiencies (PCEs) based on the device structure of ITO/PEDOT:PSS/polymer:PC71 BM/Ca/Al exhibit a large distinction (1.61% forP1, 0.53% forP2 and 2.73% forP3 ) under optimal device fabrication conditions. The optimized devices based onP3 :PC71 BM blends with a relatively higher mobility (2.84 × 10 −5 cm 2 V −1 s −1 ) show the best PCE under air mass 1.5 global (AM 1.5 G) irradiation of 100 mW cm −2, which is in good agreement with its high current density and light absorption property. Accordingly, the TI unit can be used as the efficient donor units for D–A conjugated donor materials for PSCs application. In addition, this work suggests that the side chains on low bandgap polymers significantly impact their molecular energy levels and the observed PCEs of the corresponding BHJ solar cells.