Morphology Development in Amorphous Polymer:Fullerene Photovoltaic Blend Films During Solution Casting
Morphology Development in Amorphous Polymer:Fullerene Photovoltaic Blend Films During Solution Casting
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DOI：
10.1002/adfm.201301922
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发表时间：
2014-02
影响因子：
19
通讯作者：
Andrew J Pearson;Tao Wang;A. Dunbar;Hunan Yi;Darren C. Watters;D. Coles;P. Staniec;A. Iraqi;Richard A. L. Jones;David G Lidzey
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文献类型：
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作者：
Andrew J Pearson;Tao Wang;A. Dunbar;Hunan Yi;Darren C. Watters;D. Coles;P. Staniec;A. Iraqi;Richard A. L. Jones;David G Lidzey
报道了在有机光伏器件中应用的聚合物：富勒烯共混体系PCDTBT：PC70BM 1：4wt%溶液浇注过程中薄膜结构的演变。利用掠入射广角X射线散射和椭圆偏振光谱测量的互补技术，确定了在薄膜形成过程中发生的一些不同的过程。这包括富勒烯分子在纳米级聚集体中的生长，这种聚集体的开始与材料在浇注溶剂中达到的溶解极限一致。从薄膜的富PCDTBT相的布拉格散射的明显延迟表明，对于这里研究的薄膜成分，PC70BM的聚集先于共轭聚合物的弱自组织。这一行为与许多不同聚合物的干燥动力学进行了比较：富勒烯混合物每种都含有高质量分数的富勒烯分子，并确定了一系列可比的固体浓度，超过这一范围，富勒烯聚集体就会从溶液中析出。这些观察结果提供了对相对无定形聚合物：用于有机光伏应用的富勒烯混合物的结构发展的洞察，并可能有助于这类材料的未来优化。
The evolution of film structure is reported during solution casting of PCDTBT:PC70BM 1:4 wt%, a polymer:fullerene blend system that finds application in an organic photovoltaic device. Using the complimentary techniques of grazing‐incidence wide‐angle X‐ray scattering and spectroscopic ellipsometry, a number of distinct processes that occur during film formation are identified. This includes the growth of fullerene molecules into nanoscale aggregates, the onset of which coincides with the solubility limit of the material in the casting solvent being reached. An apparent delay in Bragg scatter from the PCDTBT‐rich phase of the film suggests that, for the film composition studied here, the aggregation of PC70BM precedes weak self‐organisation of the conjugated polymer. This behaviour is compared with the drying dynamics of a number of different polymer:fullerene blends that each contain a high weight fraction of fullerene molecules, and a range of comparable solid concentrations are identified beyond which the precipitation of fullerene aggregates from solution occurs. These observations provide an insight into the development of structure in relatively amorphous polymer:fullerene blends for organic photovoltaic applications and potentially assists the future optimisation of this category of materials.