Thermodynamic Control over Molecular Aggregate Assembly Enables Tunable Excitonic Properties across the Visible and Near-Infrared
Thermodynamic Control over Molecular Aggregate Assembly Enables Tunable Excitonic Properties across the Visible and Near-Infrared
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DOI：
10.1021/acs.jpclett.0c02204
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发表时间：
2020-10-01
影响因子：
5.7
通讯作者：
Caram, Justin R.
中科院分区：
文献类型：
--
作者：
Deshmukh, Arundhati P.;Bailey, Austin D.;Caram, Justin R.
花青染料的H-/J-聚集体内的特定分子排列使得具有非凡的电子物理性质，包括长程激子离域、极端蓝/红移和激子超辐射。尽管有大量关于花青聚集体的文献，但驱动自组装到优选的H-或J-聚集状态的设计原理是未知的。我们通过独立控制溶剂/非溶剂比、离子强度或染料浓度来调整自组装的热力学，从而获得可预测地稳定单体（H-/J-聚集体）的广泛条件。扩散有序光谱，低温电子显微镜，和原子力显微镜一起揭示了单体，H-聚集的二聚体，和扩展的J-聚集的2D单层之间的动态平衡。我们构建了一个模型，预测的平衡组合物的范围内的标准吉布斯自由能，提供了一个巨大的聚集空间，我们使用上述溶剂化因子访问。我们证明了这种方法的普遍性之间的几个片材形成花青染料与可调的反射跨越可见光，近，短波红外波长。
Specific molecular arrangements within H-/J-aggregates of cyanine dyes enable extraordinary photophysical properties, including long-range exciton delocalization, extreme blue/red shifts, and excitonic superradiance. Despite extensive literature on cyanine aggregates, design principles that drive the self-assembly to a preferred H- or J-aggregated state are unknown. We tune the thermodynamics of self-assembly via independent control of the solvent/nonsolvent ratio, ionic strength, or dye concentration, obtaining a broad range of conditions that predictably stabilize the monomer ( H-/ J-aggregate). Diffusion-ordered spectroscopy, cryo-electron microscopy, and atomic force microscopy together reveal a dynamic equilibrium between monomers, H-aggregated dimers, and extended J-aggregated 2D monolayers. We construct a model that predicts the equilibrium composition for a range of standard Gibbs free energies, providing a vast aggregation space which we access using the aforementioned solvation factors. We demonstrate the universality of this approach among several sheet-forming cyanine dyes with tunable absorptions spanning visible, near, and shortwave infrared wavelengths.