Department of Physics, University of Konstanz, POB 680, 78457 Konstanz, Germany.
Sci Rep. 2016 Sep 1;6:32434. doi: 10.1038/srep32434.
Polymer morphology and aggregation play an essential role for efficient charge carrier transport and charge separation in polymer-based electronic devices. It is a common method to apply the H-aggregate model to UV/Vis or photoluminescence spectra in order to analyze polymer aggregation. In this work we present strategies to obtain reliable and conclusive information on polymer aggregation and morphology based on the application of an H-aggregate analysis on UV/Vis and photoluminescence spectra. We demonstrate, with P3HT as model system, that thickness dependent reflection behavior can lead to misinterpretation of UV/Vis spectra within the H-aggregate model. Values for the exciton bandwidth can deviate by a factor of two for polymer thicknesses below 150 nm. In contrast, photoluminescence spectra are found to be a reliable basis for characterization of polymer aggregation due to their weaker dependence on the wavelength dependent refractive index of the polymer. We demonstrate this by studying the influence of surface characteristics on polymer aggregation for spin-coated thin-films that are commonly used in organic and hybrid solar cells.
聚合物形态和聚集态对于聚合物基电子器件中有效的电荷载流子输运和电荷分离起着至关重要的作用。在紫外/可见吸收光谱或光致发光光谱中应用 H-聚集模型来分析聚合物聚集态是一种常用的方法。在这项工作中，我们提出了一些策略，通过在紫外/可见吸收光谱和光致发光光谱中应用 H-聚集分析，来获得关于聚合物聚集态和形态的可靠且明确的信息。我们以 P3HT 为模型体系证明，厚度相关的反射行为可能导致 H-聚集模型中紫外/可见吸收光谱的错误解释。对于厚度低于 150nm 的聚合物，激子带宽的值可能会偏离两倍。相比之下，由于光致发光光谱对聚合物折射率的波长依赖性的依赖性较弱，因此它们是表征聚合物聚集态的可靠基础。我们通过研究旋涂薄膜的表面特性对聚合物聚集态的影响来证明这一点，旋涂薄膜通常用于有机和混合太阳能电池。
