高效全聚合物太阳能电池的纳米尺度调控

In the past few years, all-polymer solar cells with n-type conjugated polymers as acceptors have attracted much attention. However, in comparison to the high power conversion efficiency (PCE) of the organic solar cells based on p-type conjugated polymer and PCBM blends, the PCE of all-polymer solar cells is still relatively low (<3%). There are two main reasons. First. The n-type conjugated polymers with high electron mobility are rare. Second. Due to entropy-driven phase separation, the p-/n-type conjugated polymer blend easily form extra-large domain size, which hinders the exciton transfer and split, thus resulting in low PCE. This project leader has designed and synthesized a series of novel n-type conjugated polymers with high electron carrier mobilities. The preliminary results showed that they are potentially excellent acceptors for all-polymer solar cells. In this project, we will employ two methods to achieve high PCE all-polymer solar cells and explore a theoretical model to understand the relationship between morphology of polymer blends and solar cell performance. First. In combination of DFT theoretical study and preliminary experimental results, a series of new building blocks will be designed and synthesized. By classic copolymerization methods, novel n-type conjugated polymers with or without light cross-linkable functional groups will be synthesized and characterized. These contributions will be meaningful to explore a theoretical model of understanding the relationship of the molecular structure and the solid state properties. Second. Through device engineering and light cross-linking of the n-type conjugated polymers, the domain size of the all-polymer blends will be tuned and stablized to facilitate the exciton transfer and split. This study will result in a high PCE and long life time all-polymer solar cell, furthermore a deeper understanding of the mechanism of phase separation in polymer blends, and a new theoretical model to guide future all-polymer solar cells research.

以n-型共轭聚合物为受体的全聚合物太阳能电池近年来逐渐成为研究热点。然而，目前全聚合物太阳能电池目前的转换率还比较低(<3%)。这主要有两个原因：1.缺乏高电子迁移率的n-型共轭聚合物；2.p-型/n-型聚合物的混合物易产生熵变诱导的相分离，而形成形态过大的富集相,不利于激子的迁移和分离。申请者已成功的设计并合成了具有高电子迁移率的新型n-型高分子聚合物,初步研究结果表明其是优异的受体材料。在本课题中，一方面，结合DFT计算和实验结果，从分子层面设计新型的n-型共轭聚合物以进一步提高其性能，并构建分子结构和聚集态性能关系的理论模型；另一方面，通过分子层面的功能团设计和器件制备优化，实现给体和受体富集态纳米级别的形态控制，促进激子转移和分离，最终实现高转换率和长使用寿命的全聚合物太阳能电池；进一步理解共轭聚合物共混物的相分离机理并探讨新的理论模型。

全聚合物太阳能电池近年来得到了迅速的发展；然而，目前的全聚合物太阳能电池的能量转换率还偏低，这主要有两个原因：1.缺乏高电子迁移率的n-型共轭聚合物；2.p-型/n-型聚合物的混合物易产生熵变诱导的相分离，而产生过大的富集相,不利于激子的迁移和分离。本项目以密度泛函理论为基础，将共平面的反-1,2-二(2-噻吩基)乙烯分子、碲吩分子和非共平面的三乙胺分子、异靛蓝分子分别与奈二酰亚胺和苝二酰亚胺分子进行共聚，设计、合成并表征了一系列新型的n-型共轭聚合物，研究了分子结构与共轭聚合物光物理性能的关系；然后，基于合成的n-型共轭聚合物，构建了一系列全聚合物太阳能电池和光电探测器；通过分子层面官能团的设计和聚集态纳米形貌的调控，对光电器件进行了系统的优化，得到了性能优异的全聚合物光电转换器件，并且结合先进的薄膜表征手段（X-射线衍射、透射电镜、原子力显微镜等），探讨了薄膜纳米形貌与光电器件性能的关系，有助于进一步设计并合成用于高效全聚合物太阳能电池的新型n-型共轭聚合物。