Multiblock co-oligomers with predefined and monodisperse segments and thermodynamicallystable lamellar morphology for non-fullerene solar cells

POPULAR研究单位项目1的目标是控制和预测非富勒烯（NFA）太阳能电池的形态，并提高其形态的长期稳定性。使用单分散块的供体-受体多块共聚物，我们将通过自组装产生热力学稳定的层状形态。片层宽度和长周期将由供体和受体段的长度来预测和决定。化学上，低聚供体片段将基于最先进的材料PM6的重复单元，而受体片段将基于已建立的PNDIT2。作为一个关键特征，具有明确的端基的单分散低聚物将被制备并纳入多块共低聚物。与文献报道的共轭供体-受体嵌段共聚物不同，嵌段的单分散性质将允许非常明确的界面。此外，可以完全消除与再现性和批次间变化相关的问题。此外，在给体段和受体段之间使用非共轭连接体将为增强两段的分离提供空间，并且还可以防止电荷重组。在第二个四年期间，这种方法将扩展到更多的非富勒烯受体，PNDIT2将被更高性能的受体如Y6所取代。POPULAR联盟将利用分子、光电、热、结构和器件相关方法对迄今未知的多块共聚物进行全面研究，并最终阐明其在印刷太阳能电池中的适用性。

The goal of Project 1 within the Research Unit POPULAR is to control and predict morphology of non-fullerene (NFA) solar cells and increase their morphological long-term stability. Using donor--acceptor multiblock co-oligomers with monodisperse blocks, we will generate thermodynamically stable, lamellar morphologies by virtue of self-assembly. Lamellar widths and long periods will be predicted and determined by the length of the donor and acceptor segments. Chemically, the oligomeric donor segments will be based on the repeat units of the state-of-the-art material PM6, while the acceptor segment will be based on established PNDIT2. As a key feature, monodisperse oligomers with well-defined end groups will be prepared and incorporated into multiblock co-oligomers. Unlike literature reports on conjugated donor--acceptor block copolymers, the monodisperse nature of the blocks will allow for extremely well-defined interfaces. Moreover, issues related to reproducibility and batch-to-batch variations can be entirely eliminated. Furthermore, usage of non-conjugated linkers between donor and acceptor segments will give room to enhanced segregation of the two segments and additionally prevent charge recombination. In the second four-year period, this approach will be extended to further non-fullerene acceptors with PNDIT2 being substituted by yet higher performing acceptors such as Y6. The hitherto unknown multiblock co-oligomers will be investigated comprehensively by the POPULAR consortium using molecular, opto-electronic, thermal, structural and device-related methods, and their suitability for printed solar cells will finally be elucidated.