9-Fluorenone and 9,10-anthraquinone potential fused aromatic building blocks to synthesize electron acceptors for organic solar cells?

New Journal of Chemistry Pub Date: 2017-02-27 DOI: 10.1039/C6NJ03938C

Abstract

In this work, for the first time we used two novel fused aromatic conjugated electron withdrawing moieties 9-fluorenone and 9,10-anthraquinone, respectively, to design two non-fullerene acceptors and evaluated their viability in solution-processable organic solar cells (OSCs). 9-Fluorenone and 9,10-anthraquinone were used as core electron withdrawing blocks in combination with another common strong electron accepting diketopyrrolopyrrole (DPP) end-capping group. The compounds 6,6′-(5,5′-(9-oxo-9H-fluorene-2,7-diyl)bis(thiophene-5,2-diyl))bis(2,5-bis(2-butyloctyl)-3-(thiophen-2-yl)pyrrolo[3,4-c]pyrrole-1,4(2H,5H)-dione) (DPP-FN-DPP) and 6,6′-(5,5′-(9,10-dioxo-9,10-dihydroanthracene-2,6-diyl)bis(thiophene-5,2-diyl))bis(2,5-bis(2-butyloctyl)-3-(thiophen-2-yl)pyrrolo[3,4-c]pyrrole-1,4(2H,5H)-dione) (DPP-ANQ-DPP) were synthesized via a Suzuki coupling reaction and characterized completely. The new acceptors exhibit good solubility in common organic solvents and good thermal stability with 5% weight loss above 360 °C. DPP-FN-DPP and DPP-ANQ-DPP possess a broad absorption band at 300–700 nm with optical band-gaps of 1.75 and 1.71 eV, respectively. The use of different core acceptor building blocks resulted in a difference in LUMO and HOMO energy levels. Inverted OSC devices employing P3HT as the donor polymer and DPP-FN-DPP and DPP-ANQ-DPP as acceptors yielded quite high open-circuit voltages (VOC) of 0.85–0.98 V, benefiting from the relatively low-lying LUMO energy levels of the two acceptors. Among both, OSC devices based on DPP-FN-DPP as acceptor exhibits the highest performance with a VOC of 0.97 V, a short-circuit current density (JSC) of 3.2 mA cm?2, a fill factor (FF) of 37%, and an overall power conversion efficiency of 1.2%.

Graphical abstract: 9-Fluorenone and 9,10-anthraquinone potential fused aromatic building blocks to synthesize electron acceptors for organic solar cells
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