This study proposes a "fine molecular engineering" strategy to address the trade-off between efficiency and stability by designing non-fullerene acceptors (NFAs). Based on 7C-2F with a 1,4-diazahexane core, three NFAs were synthesized by selectively controlling the side chain length and the degree of π-conjugation of the terminal groups. The results show that shortening the side chain (7C-BO-2F and 7C-eC9-2F) or extending the π-conjugation of the terminal groups (7C-N2F) both improve molecular crystallinity, shorten the π-π stacking distance, and suppress nonradiative energy loss. In bulk heterojunction devices, the PM6:7C-eC9-2F system achieved a PCE of 19.67% with an energy loss of only 0.539 eV. Devices based on 7C-eC9-2F exhibit excellent photostability and thermal stability: under continuous illumination, the device's T 80 reaches 2728 h⁻¹; at 65 °C, its T 80 reaches 1242 h⁻¹, significantly outperforming other control systems. Furthermore, when these acceptors are applied to quasi-planar heterojunction structures, excellent photovoltaic performance is also obtained, demonstrating good fabrication adaptability. In summary, precise molecular engineering provides a reliable pathway to obtaining high-efficiency, low-energy-loss, and intrinsically stable OPVs, laying the foundation for the practical application of next-generation organic photovoltaic devices. The article was published as an open access Research Article in CCS Chemistry , the flagship journal of the Chinese Chemical Society.
Background information:
OPVs offer a promising technological route for renewable energy, but balancing high power conversion efficiency (PCE) with long-term stability remains a significant challenge. Currently, improving the PCE of OPVs hinges on suppressing non-radiative energy loss, while long-term stability is also a core issue that urgently needs to be addressed. Therefore, developing organic photovoltaic systems with both high efficiency and high stability through novel molecular design strategies is of great importance. Based on existing research, this paper, starting from molecular design strategies that synergistically improve device efficiency and stability, and combining different device fabrication processes, develops a series of novel NFAs with excellent photoelectric properties and photovoltaic performance, greatly enriching the high-performance photovoltaic material system.
Highlights of this article:
The authors provide an effective approach to simultaneously improve the efficiency and stability of OPVs through sophisticated molecular engineering of NFAs. This performance improvement mainly stems from optimized molecular aggregation states, improved crystallinity, suppressed nonradiative recombination, and a clear and well-defined microstructure. These factors collectively promote efficient charge generation and transport while ensuring morphological durability under thermal and optical stress. Furthermore, the excellent performance exhibited by these NFAs in Q-PHJ devices highlights their broad applicability across various fabrication processes.
Summary and Outlook:
This work highlights the crucial role of customized molecular design in overcoming the efficiency-stability tradeoff in OPVs, providing practical molecular design guidance for developing next-generation high-performance, intrinsically stable OPVs and accelerating their transformation into commercial devices.
This work was published as a Research Article in CCS Chemistry . Dr. Mingpeng Li, Dr. Waqar Ali Memon, and postdoctoral fellow Xue Lai, all senior visiting scholars in the Department of Chemistry at Southern University of Science and Technology (SUSTech), are co-first authors, and Professor Feng He of the Department of Chemistry at SUSTech is the corresponding author. This research was supported by the National Natural Science Foundation of China and the Shenzhen Natural Science Foundation.
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About the journal: CCS Chemistry is the Chinese Chemical Society’s flagship publication, established to serve as the preeminent international chemistry journal published in China. It is an English language journal that covers all areas of chemistry and the chemical sciences, including groundbreaking concepts, mechanisms, methods, materials, reactions, and applications. All articles are diamond open access, with no fees for authors or readers. More information can be found at https://www.chinesechemsoc.org/journal/ccschem .
About the Chinese Chemical Society: The Chinese Chemical Society (CCS) is an academic organization formed by Chinese chemists of their own accord with the purpose of uniting Chinese chemists at home and abroad to promote the development of chemistry in China. The CCS was founded during a meeting of preeminent chemists in Nanjing on August 4, 1932. It currently has more than 120,000 individual members and 184 organizational members. There are 7 Divisions covering the major areas of chemistry: physical, inorganic, organic, polymer, analytical, applied and chemical education, as well as 31 Commissions, including catalysis, computational chemistry, photochemistry, electrochemistry, organic solid chemistry, environmental chemistry, and many other sub-fields of the chemical sciences. The CCS also has 10 committees, including the Woman’s Chemists Committee and Young Chemists Committee. More information can be found at https://www.chinesechemsoc.org/ .
CCS Chemistry
10.31635/ccschem.026.202608095
Experimental study
Not applicable
Subtle Structural Tailoring Enables Improved Crystallinity and Miscibility for High-Efficiency, Stable Organic Photovoltaics
11-Sep-2026
There is no conflict of interest to report.