Structure formation in perfluoropentacene:diindenoperylene blends and its impact on transient effects in the optical properties studied in real-time during growth.
Structure formation in perfluoropentacene:diindenoperylene blends and its impact on transient effects in the optical properties studied in real-time during growth.
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DOI：
10.1063/1.4827868
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发表时间：
2013-11
期刊：
影响因子：
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通讯作者：
K. Broch;A. Gerlach;C. Lorch;J. Dieterle;J. Novák;A. Hinderhofer;F. Schreiber
中科院分区：
文献类型：
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作者：
K. Broch;A. Gerlach;C. Lorch;J. Dieterle;J. Novák;A. Hinderhofer;F. Schreiber
我们讨论了由于全氟并五苯（PFP）和二茚并二苯（DIP）的尺寸失配对混合膜的结构形成和相关光学性质的有利的分子间相互作用和空间不相容性的竞争效应的结果。使用实时掠入射X射线衍射，我们调查的相干散射岛的大小l（s）作为薄膜厚度和混合比的函数。我们发现，对于PFP：DIP 1：2共混物，I（s）比纯DIP膜小~4倍，而PFP：DIP 2：1共混物的I（s）与纯PFP相比没有显著降低。然而，我们观察到所有样品的l（s）随膜厚度的增加而增加，与混合比无关。在平行的结构表征，我们调查的吸收光谱在可见光谱范围内的演变及其依赖于l（s）在原位薄膜生长过程中使用差分反射光谱。我们观察到结构顺序的变化对ε（2，xy）（E）的形状的惊人的强烈影响，这通过在1.6 nm至9.6 nm的厚度范围内的特征峰的显著演变来证明。实时实验的组合结果允许将厚度依赖性晶粒尺寸识别为在吸收光谱中观察到的瞬态效应的起源。
We discuss the result of the competing effects of favourable intermolecular interactions and steric incompatibilities due to the size mismatch of perfluoropentacene (PFP) and diindenoperylene (DIP) on the structure formation and associated optical properties in mixed films. Using real-time grazing incidence X-ray diffraction we investigate the size of coherently scattering islands l(s) as a function of film thickness and mixing ratio. We find that for PFP:DIP 1:2 blends l(s) is by a factor of ~4 smaller than in pure DIP films, while l(s) of the PFP:DIP 2:1 blends is not significantly reduced compared with pure PFP. Yet, we observe an increase in l(s) with film thickness for all of the samples, independent on the mixing ratio. In parallel with the structural characterization we investigate the evolution of the absorption spectra in the visible spectral range and its dependence on l(s) in situ during film growth using differential reflectance spectroscopy. We observe a surprisingly strong effect of changes in the structural order on the shape of ε(2, xy)(E), evident by a pronounced evolution of characteristic peaks in the thickness range from 1.6 nm to 9.6 nm. The combined results of the real-time experiments allow to identify the thickness dependent crystal grain size as the origin of the observed transient effects in the absorption spectra.