Achieving high-performance ternary organic photovoltaics by introducing the unfused-ring core based small-molecule acceptors
Bing-Huang Jiang a, Yu-Chi You b, Chih-Ping Chen a, Ken-Tsung Wong b
a Department of Materials Engineering, Ming Chi University of Technology, New Taipei City 243, Taiwan
b Department of Chemistry, National Taiwan University, Taipei 10617, Taiwan
Asia-Pacific International Conference on Perovskite, Organic Photovoltaics and Optoelectronics
Proceedings of Asia-Pacific International Conference on Perovskite, Organic Photovoltaics and Optoelectronics (IPEROP23)
Kobe, Japan, 2023 January 22nd - 24th
Organizers: Seigo Ito, Hideo Ohkita and Atsushi Wakamiya
Poster, Bing-Huang Jiang, 049
Publication date: 21st November 2022

Attributed to the strategy of multi-component, organic photovoltaics (OPVs) have achieved power conversion efficiencies (PCE) of over 19%. Small-molecule based non-fullerene acceptors (NFA) having large-fused core structures are widely used as guest acceptors to form the ternary OPV. In contrast, the study based on the unfused-ring NFA as guest acceptors for ternary OPVs is still lacked, even though it has some advantages such as simplifying the synthetic process and reducing the cost. Herein, we reported a series of unfused-ring central core derived NFAs with the structure of the naphthobisthiadiazole (or derivative) unit and cyclopenta[2,1-b:3,4-b']dithiophene unit, and used malononitrile, 2-(3-oxo-2,3-dihydro-1H-inden-1-ylidene)malononitrile and 2-(5,6-difluoro-3-oxo-2,3-dihydro-1H-inden-1-ylidene)malononitrile as terminal group. The strong intermolecular interaction of these NFA limited their performance in binary OPV. Nevertheless, they behave well as the third component and promoted the performance of the PM6:Y6-based ternary OPV over 16% which is outperformed the PM6:Y6 devices. It attributed that the NFA provided complementary absorption and allowed fine-tuning of the blend morphology, resulting in suppression of charge recombination and improvements in charge generation and collection. We observed that these NFAs incorporating various end groups that displayed different interactions with the Y6 and affected the open-circuit voltage of respective devices. Our study might benefit further understanding the complex mechanism of ternary OPV that is governed by the nanomorphology and energetics. We demonstrated that the unfused-ring core based NFAs as a guest acceptor had a great potential in achieving high-performance ternary OPVs. 

We thank the Ministry of Science and Technology of Taiwan (MOST 107-2113-M-002-019-MY3, 110-2113-M-002-008-MY3) for providing financial support.

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