Recently, Professor Zhan Xiaowei's group from the College of Engineering at Peking University made new progress in non-fullerene acceptors for organic solar cells (OSCs). They developed a new fluorinated fused-ring electron acceptor (FREA) with 3D stacking and exciton and charge transport ( Adv. Mater. , DOI: 10.1002/adma.202000645).
In 2015, the Zhan group pioneered the concept of FREA and invented the landmark molecule ITIC ( Adv. Mater. , 2015, 27, 1170-1174, cited 1590 times). In 2017, they firstly introduced fluorinated 2-(3-oxo-2,3-dihydroinden-1-ylidene) -malononitrile, 1FIC and 2FIC, in FREAs ( J. Am. Chem. Soc. , 2017, 139, 1336-1343, cited 547 times; Adv. Mater. , 2017, 29, 1700144, cited 549 times). Now, all the best non-fullerene acceptors are based on 1FIC/2FIC.
Most recently, they proposed a new design strategy to construct FREAs via fluorination of both end-groups and side-chains. Close 3D stacking network is formed due to 3D non-covalent interactions caused by F atoms on both end-groups and side-chains, which is beneficial to efficient 3D exciton and charge transport. The OSCs based on FINIC with fluorinated end-groups and side-chains show an efficiency of 14.0%, much higher than that of the nonfluorinated INIC-based cells (5.1%).
The research work was supported by the National Nature Science Foundation of China and Basic Research Promotion Project of Peking University.
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Advanced Materials