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A chlorinated nonacyclic carbazole-based acceptor affords over 15% efficiency in organic solar cells

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Abstract

In this contribution, a dithienocyclopentacarbazole (DTC)-based and two dithieno[3,2-b]thiophenecyclopentacarbazole (DTTC)-based non-fullerene acceptors (NFAs) named DTC-4F, DTTC-4F and DTTC-4Cl were exploited to elucidate the effects of conjugation extension and end group chlorination. DTTC-4F was designed through conjugation extension on the basis of DTC-4F by fusing one additional thiophene on both flanks of the heptacyclic DTC core, generating the nonacyclic DTTC core. Compared with DTC-4F, DTTC-4F features up-shifted energy levels, red-shifted absorption and enhanced π–π interaction. PM6:DTTC-4F exhibits a decent PCE of 13.89% with a VOC of 0.95 V, a JSC of 21.66 mA cm−2 and a FF of 67.60%. Although DTTC-4F affords a reduced FF compared to DTC-4F, a DTTC-4F-based device delivers a higher PCE than DTC-4F-based devices due to the extended absorption range of DTCC-4F in comparison with DTC-4F. Since chlorinated NFAs are known to possess stronger π–π interaction than fluorinated NFAs, DTTC-4Cl was therefore synthesized by end-capping DTTC core with 2Cl-IC groups instead of 2F-IC groups. Moreover, DTTC-4Cl demonstrates a red-shifted absorption in comparison with DTTC-4F, which is beneficial for light-harvesting. Overall, PM6:DTTC-4Cl affords an outstanding PCE of 15.42% with a VOC of 0.92 V, a JSC of 22.64 mA cm−2 and a FF of 74.04%, which is the record PCE observed in carbazole-based NFAs.

Graphical abstract: A chlorinated nonacyclic carbazole-based acceptor affords over 15% efficiency in organic solar cells

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Supplementary files

Article information


Submitted
17 Nov 2019
Accepted
08 Dec 2019
First published
11 Dec 2019

J. Mater. Chem. A, 2020, Advance Article
Article type
Communication

A chlorinated nonacyclic carbazole-based acceptor affords over 15% efficiency in organic solar cells

T. Chen, K. Peng, Y. Lin, Y. Su, K. Ma, L. Hong, C. Chang, J. Hou and C. Hsu, J. Mater. Chem. A, 2020, Advance Article , DOI: 10.1039/C9TA12605H

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