Measuring Temperature-Dependent Miscibility for Polymer Solar Cell Blends: An Easily Accessible Optical Method Reveals Complex Behavior
Measuring Temperature-Dependent Miscibility for Polymer Solar Cell Blends: An Easily Accessible Optical Method Reveals Complex Behavior
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DOI：
10.1021/acs.chemmater.8b00889
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发表时间：
2018-06-26
影响因子：
8.6
通讯作者：
Ade, Harald
中科院分区：
文献类型：
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作者：
Peng, Zhengxing;Jiao, Xuechen;Ade, Harald
在本体异质结聚合物太阳能电池（PSC）中，共轭聚合物给体和小分子受体之间的分子级混合对获得理想的形貌和良好的器件稳定性起着至关重要的作用。最近已经表明，这种混合的热力学极限可以量化的液相线的结晶度，在小分子晶体的存在下，在非晶相的小分子受体的组合物，然后转换为Flory-Huggins相互作用参数chi。这种转换映射出无定形的可结晶性。此外，最近建立了PSC器件的填充因子与chi之间的定量关系。然而，这种液相线混溶性的常用测量方法（扫描透射X射线显微镜）并不容易获得。在这里，我们描绘了一种基于普通可见光显微镜和紫外-可见吸收光谱的方法，以取代X射线测量。为了证明这种技术和方法的可行性，表征了各种共轭聚合物（PffET 4 T-C9 C13、PDPP 3 T PBDT-TS 1、PTB 7-Th和FTAZ）及其与富勒烯或非富勒烯小分子（PC 71 BM、PC61 BM和EH-IDTBR）的相容性。这一方法的建立将为更广泛地利用液相线结晶度和临界结晶度-函数关系来优化器件性能和获得良好的稳定性铺平道路。
In bulk-heterojunction polymer solar cells (PSC), the molecular-level mixing between conjugated polymer donors and small-molecule acceptors plays a crucial role in obtaining a desirable morphology and good device stability. It has been recently shown that the thermodynamic limit of this mixing can be quantified by the liquidus miscibility, the composition of the small-molecule acceptor in amorphous phases in the presence of small-molecule crystals, and then converted to the Flory-Huggins interaction parameter chi. This conversion maps out the amorphous miscibility. Moreover, the quantitative relations between chi and the fill factor of PSC devices were established recently. However, the commonly used measurement of this liquidus miscibility, scanning transmission X-ray microscopy, is not easily and readily accessible. Here, we delineate a method based on common visible light microscopy and ultraviolet-visible absorption spectroscopy to replace the X-ray measurements. To demonstrate the feasibility of this technique and methodology, a variety of conjugated polymers (PffET4T-C9C13, PDPP3T PBDT-TS1, PTB7-Th, and FTAZ) and their miscibility with fullerenes or nonfullerene small molecules (PC71BM, PC61BM, and EH-IDTBR) are characterized. The establishment of this methodology will pave the way to a wider use of the liquidus miscibility and the critical miscibility-function relations to optimize the device performance and obtain good stability in PSCs and other devices.