Processing solvent additives in polymer:fullerene bulk heterojunction systems are known as a promising method to enhance photovoltaic performance. It is generally agreed that solvent additives enable polymers to have a high degree of molecular order which increases the device performance. However, the understanding of the efficiency enhancement is not complete. There is a lack of insight regarding the quantitative determination of the molecular miscibility between polymer and fullerene as well as the inner morphology changes induced by the additives. In this work, understanding of the influence of the solvent additive 1,8‐octanedithiol (ODT) is provided on the classic system poly(3‐hexylthiophene‐2,5‐diyl):[6,6]‐phenyl‐C61 butyric acid methyl ester (P3HT:PCBM) films. The impact on polymer crystallinity, surface structure, inner morphology, and quantitative molecular miscibility of P3HT and PCBM is studied as a function of ODT volume concentration. The crystallinity is probed with absorption spectroscopy and grazing incidence wide‐angle X‐ray scattering. The morphology and miscibility are characterized via atomic force microscopy and time‐of‐flight grazing incidence small angle neutron scattering. Besides an increased crystallinity and prominent phase separation, ODT increases the solubility of PCBM in P3HT and reduces the size of amorphous P3HT domains. Moreover, solvent processing with a high ODT concentration alters the vertical material composition of the active layer.

中文翻译：

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溶剂添加剂1,8-辛二酸对P3HT：PCBM太阳能电池的影响

在聚合物：富勒烯本体异质结体系中加工溶剂添加剂被认为是增强光伏性能的一种有前途的方法。通常认为，溶剂添加剂可使聚合物具有较高的分子序度，从而提高器件性能。但是，对效率增强的理解还不完整。缺乏对聚合物与富勒烯之间的分子相容性以及由添加剂引起的内部形态变化的定量测定的见识。在这项工作中，提供了对溶剂体系1,8-辛二酸（ODT）对经典体系聚（3-己基噻吩-2,5-二基）的影响的理解：[6,6]-苯基-C61丁酸甲酯（P3HT：PCBM）膜。对聚合物结晶度，表面结构，内部形态，并研究了P3HT和PCBM的定量分子混溶性与ODT体积浓度的关系。用吸收光谱和掠入射的广角X射线散射探测结晶度。通过原子力显微镜和飞行时间掠射入射小角中子散射来表征形态和可混溶性。除增加结晶度和明显的相分离外，ODT还增加了PCBM在P3HT中的溶解度，并减小了无定形P3HT域的大小。而且，具有高ODT浓度的溶剂处理改变了活性层的垂直材料组成。通过原子力显微镜和飞行时间掠射入射小角中子散射来表征形态和可混溶性。除增加结晶度和明显的相分离外，ODT还增加了PCBM在P3HT中的溶解度，并减小了无定形P3HT域的大小。而且，具有高ODT浓度的溶剂处理改变了活性层的垂直材料组成。通过原子力显微镜和飞行时间掠射入射小角中子散射来表征形态和可混溶性。除增加结晶度和明显的相分离外，ODT还增加了PCBM在P3HT中的溶解度，并减小了无定形P3HT域的大小。而且，具有高ODT浓度的溶剂处理改变了活性层的垂直材料组成。