Dense chromophore systems have been proposed as an alternative approach to creating solid-state triplet–triplet annihilation upconversion (TTA-UC) materials. In order to extend this system to polymer-based TTA-UC materials, a new method for the in situ preparation of dense chromophore systems in poly(vinyl alcohol) (PVA) was developed using a mechanical stretching technique. The chromophores used in this study were newly synthesised to dissolve homogeneously in a PVA aqueous solution. These chromophores exhibited a blue upconverted emission in MeOH solution upon excitation with a 532 nm green laser. Remarkably, a clear upconversion emission was observed from the chromophore-blended PVA films even under ambient conditions after the stretching process. In addition, a correlation between the elongation length of the films and the ratio of UC emission/phosphorescence was clearly observed. The stretching process made the chromophores more condensed in the oriented and cross-linked polymer chains, thereby creating favourable conditions for triplet–triplet annihilation.

中文翻译：

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使用新型拉伸聚乙烯醇薄膜增强了空气中的上转换辐射†

已经提出了密集的生色团系统作为创建固态三重态-三重态an灭上转换（TTA-UC）材料的替代方法。为了将此系统扩展到基于聚合物的TTA-UC材料，一种新的原位方法使用机械拉伸技术开发了在聚乙烯醇（PVA）中致密发色团体系的制备方法。本研究中使用的生色团是新合成的，可均匀溶解在PVA水溶液中。在532 nm绿色激光激发后，这些生色团在MeOH溶液中显示出蓝色上转换的发射光。显着地，即使在拉伸过程之后在环境条件下，也从发色团混合的PVA膜中观察到清晰的上转换发射。另外，清楚地观察到膜的伸长长度与UC发射/磷光比之间的相关性。拉伸过程使生色团在定向和交联的聚合物链中更凝聚，从而为三重态-三重态an灭创造了有利条件。