Recently, a team led by Lu Shirong from the School of Materials Science and Engineering, in collaboration with Zhejiang University and the Chongqing Institute of Green and Smart Technology of the Chinese Academy of Sciences, achieved a breakthrough in the field of organic photovoltaic cells by employing a novel liquid additive strategy. This achievement, titled “Simultaneously improving the efficiencies of organic photovoltaic devices and modules by finely manipulating the aggregation behaviors of Y-series molecules” was published in the journal Energy & Environmental Science (IF=32.4). Postdoctoral Fellow Wang Yufei, Researcher Lu Shirong, and Professor Yang Yang are the co-corresponding authors of the paper, with Li Yaohui (a jointly cultivated doctoral candidate by TU, Chongqing Institute of Green and Smart Technology, and Zhejiang University) as the first author. TU is the first correspondence unit for the paper.

Introducing electron-deficient cores (such as BTP, dithieno[3.2-b]pyrrole[1,2-a]benzothiazole) is considered an effective strategy to regulate the electron-vibrational coupling, delocalization, and molecular packing of high-performance Y-series non-fullerene acceptors (NFA). However, these methods often fail to achieve precise control over the various aggregation behaviors of Y-series NFA, which is one of the key factors limiting the enhancement of the final device performance. In this study, Professor Lu Shirong’s team from TU and Professor Yang Yang’s team from Zhejiang University proposed a novel liquid additive—electronegative alkanes, which is used to enhance non-covalent interactions and promote electron coupling. The related results were published in the journal Energy & Environmental Science on November 20, 2024. The study showed that electronegative alkanes selectively act on the BTP core of Y-series small molecules, promoting rapid nucleation and crystallization, and enhancing molecular packing and aggregation. Additionally, the research team observed that this selective action is well-preserved in the blended active layer, thereby optimizing the charge transport in the bulk heterojunction and reducing trap-assisted recombination. By this strategy, efficiencies of 17.60%, 18.80%, 18.36%, and 19.51% were achieved in the PM6:Y6, PM6:BTP-ec9, PM6:L8BO, and PM6:D18:L8BO blended active layer systems respectively, and a record efficiency of 14.08% was achieved on thick films (≥200 nm) with a large area (19.31 cm²). This work provided guidance for thick film modules.

Achievement link: https://doi.org/10.1039/D4EE04378B