An Indacenodithiophene–Quinoxaline Polymer Prepared by Direct Arylation Polymerization for Organic Photovoltaics

• Published in: Macromolecules Vol. 49; no. 2; pp. 527 - 536
• Main Authors: Chen, Shanshan, Lee, Kyu Cheol, Zhang, Zhi-Guo, Kim, Dong Suk, Li, Yongfang, Yang, Changduk
• Format: Journal Article
• Language: English
• Published: American Chemical Society 26.01.2016
• ISSN: 0024-9297; 1520-5835
• DOI: 10.1021/acs.macromol.5b02324

Seeking preparation of high-performance donor–acceptor (D–A) polymers based on bare thiophene units in a more environmentally friendly and faster way, we have carried out a direct arylation polymerization (DAP) of two starting β-unprotected thiophene-containing monomers (indaceno­dithiophene (IDT) and thiophene–quinoxaline–thiophene (TQ)). Through modulating DAP time and heating method, the resulting IDT–TQ polymer shows a relatively well-defined structure with low content of structural defects, as demonstrated by high temperature 1H NMR, MALDI-TOF-MS, and elemental analysis. Integrating this polymer into bulk-heterojunction solar cells with PC71BM can induce an enhanced OPV performance compared to the other structural analogues that retain a certain amount of unwanted structural defects. However, the film morphology and crystallinity are negligibly influenced by the degree of the structural defects. Through a combination of detailed electrical measurements using light intensity dependence and net photocurrent, we are able to correlate the different photovoltaic performances in structure–function relationships with the extent of the structural defects. Our study indicates that DAP is a promising asset for environmental production of many valuable thiophene-containing polymers for electroactive and photoactive applications.