Structural diffraction analysis of an anilino squaraine with branched isobutyl side chains shows crystallization into two polymorphic structures in the bulk and in spin-casted thin films. We observe multipeaked and pleochroic absorption spectra being blue-(red)-shifted for the monoclinic (orthorhombic) polymorph. We understand the packing as Coulombic molecular H-(J)-aggregates supporting Davydov splitting. Pictures of projected Davydov components in oriented thin films fit well to polarization resolved spectro-microscopy and crossed-polarized light microscopy investigations. By comparison with literature on anilino squaraines with linear alkyl side chains, we point out a general trend for steering the thin film excitonic properties by simple side chain and/or processing condition variation. Combined with the ability to locally probe the direction of transition dipole moments, this adds value to the rational design of functional thin films for optoelectronic applications, especially envisioning ultrastrong light–matter interactions.

中文翻译：

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多态和带纹理的Anilino Squaraine薄膜中的激子耦合成为人们关注的焦点

具有支化异丁基侧链的苯胺基方酸的结构衍射分析表明，在本体和旋铸薄膜中结晶为两个多晶型结构。我们观察到单峰（斜方晶）多晶型物的多峰和多色吸收光谱被蓝（红）移。我们将堆积理解为支持Davydov分裂的库仑分子H-（J）-聚集体。定向薄膜中预计的达维多夫分量的图片非常适合偏振分辨光谱显微镜和交叉偏振光显微镜研究。通过与线性阿尼利诺ino鼠的文献比较对于烷基侧链，我们指出了通过简单的侧链和/或加工条件变化来控制薄膜激子性质的总体趋势。结合局部探测跃迁偶极矩方向的能力，这为用于光电应用的功能薄膜的合理设计增加了价值，尤其是设想了超强的光-质相互作用。