A series of four perylene diimide (PDI) chromophores were prepared with increasing steric bulk on the imide substituents with the aim of retarding the effect of concentration quenching on photoluminescence, commonly observed with these dyes. Spectroscopic investigations of the compounds in dilute solution confirmed that the photophysical properties of the PDI core chromophore were not perturbed by the bulky substituents. Solid film samples containing the PDI compounds at various concentrations dispersed in a poly(methyl methacrylate) (PMMA) matrix were examined and compared to amorphous neat films as well as crystalline samples. The PDI compounds containing di-tert-butylphenyl (bPDI-3) and trityl (bPDI-4) substituents showed near unity photoluminescence quantum yield (PLQY) up to 20 mM in PMMA compared to 10% PLQY for the reference compound (bPDI-1) without molecular insulation. Surprisingly, high concentrations (>40 mM) of a phenyl-substituted PDI compound (bPDI-2) with moderate molecular insulation formed emissive aggregates that showed a higher PLQY compared to the PDI derivatives with greater steric bulk. By examining the molecular structure and solid state packing in conjunction with a series of photophysical measurements, new insights into designing highly fluorescent dyes, particularly in the solid state, were obtained. The trityl-substituted PDI compound (bPDI-4) was used in a luminescent solar concentrator with optical quantum efficiency of 54%, flux gain of 6.4, and geometric gain of 45.

中文翻译：

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高荧光分子绝缘Per二酰亚胺：浓度对光物理性质的影响

制备了一系列四个per二酰亚胺（PDI）发色团，这些酰亚胺在酰亚胺取代基上的空间体积增加，目的是阻止浓度猝灭对光致发光的影响，这种现象通常在这些染料中观察到。化合物在稀溶液中的光谱研究证实，PDI核心生色团的光物理性质不会被庞大的取代基所干扰。检查了固体膜样品，该样品包含分散在聚甲基丙烯酸甲酯（PMMA）基质中的各种浓度的PDI化合物，并与无定形纯净膜和结晶样品进行了比较。含二的PDI化合物叔-丁基苯基（bPDI-3）和三苯甲基（bPDI-4）取代基在PMMA中显示出接近20 mM的单位光致发光量子产率（PLQY），而没有分子绝缘的参考化合物（bPDI-1）的PLQY为10％。出人意料的是，具有中等分子绝缘的高浓度（> 40 mM）苯基取代的PDI化合物（bPDI-2）形成了发射聚集体，与具有更大空间体积的PDI衍生物相比，PLQY更高。通过检查分子结构和固态堆积并结合一系列光物理测量，获得了设计高荧光染料（特别是固态）的新见识。三苯甲基取代的PDI化合物（bPDI-4）用于发光太阳能集中器，其光量子效率为54％，通量增益为6.4，几何增益为45。