Issue 17, 2021

Two cyanopyridinone-capped 9,9′-bifluorenylidene derivatives as non-fullerene acceptors for organic photovoltaic cells

Abstract

Two new cyanopyridinone-capped 9,9′-bifluorenylidene derivatives, 5,5′,5′′,5′′′-(([9,9′-bifluorenylidene]-3,3′,6,6′-tetrayltetrakis(4-hexylthiophene-5,2-diyl))tetrakis(methanylylidene)) tetrakis(1-butyl-4-methyl-2,6-dioxo-1,2,5,6-tetrahydropyridine-3-carbonitrile) (A1) and 5,5′,5′′,5′′′-(([9,9′-bifluorenylidene]-2,2′,7,7′-tetrayltetrakis(4-octylthiophene-5,2-diyl))tetrakis (methanylylidene))tetrakis(1-(2-ethylhexyl)-4-methyl-2,6-dioxo-1,2,5,6-tetrahydropyridine-3-carbonitrile) (A2), were synthesized as non-fullerene small molecular acceptors for organic solar cells. The compounds exhibited excellent solubility in a variety of common organic solvents such as dichloromethane, toluene and o-dichlorobenzene due to possessing different length alkyl chains on the thiophene-bridged groups and the cyanopyridinone units. The introduction of the strong electron-withdrawing cyanopyridinone groups as the capping groups can improve the intramolecular charge transfer (ICT) and thus broaden the absorption spectra of the molecules. By changing the connection points of the capping groups in the 9,9′-bifluorenylidene core, the photophysical and electrochemical properties of the compounds can be easily adjusted. The photovoltaic performance of A1 and A2 as acceptors was investigated by fabricating solar cells with the following structure: ITO/PEDOT:PSS/PBDB-T:A1(or A2)/PDTNO/Al. The results showed that power conversion efficiencies (PCEs) of 1.01% and 1.98% were obtained using A1 and A2, respectively, as the acceptors without any treatment. After treating the active layers with solvent vapor annealing, their PCEs were increased to 1.28% and 2.94%, respectively.

Graphical abstract: Two cyanopyridinone-capped 9,9′-bifluorenylidene derivatives as non-fullerene acceptors for organic photovoltaic cells

Supplementary files

Article information

Article type
Paper
Submitted
02 Feb 2021
Accepted
26 Mar 2021
First published
27 Mar 2021

New J. Chem., 2021,45, 7637-7646

Two cyanopyridinone-capped 9,9′-bifluorenylidene derivatives as non-fullerene acceptors for organic photovoltaic cells

C. Wei, T. Zhang, Y. Zhao, Y. Zhou, M. Hailin and T. Yu, New J. Chem., 2021, 45, 7637 DOI: 10.1039/D1NJ00540E

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