Enhanced directionality of photoluminescence emission has attracted attention due to its diverse application areas ranging from single-photon sources to fluorescence sensing and bio-imaging. Utilization of null phase advance in epsilon-near-zero (ENZ) medium is an important scheme to achieve the directive emission. Despite various designs proposed for ENZ-based directive emission, most of the ENZ mediums are restricted to subwavelength structures of metallic plasmonics or inorganic dielectrics. Here, we introduce an organic ENZ film placed on top of a polymeric fluorophore film to demonstrate a directive emission. By taking advantage of the structural coherence in the P3HT film and the ENZ response in the squaraine molecular film, 42 % increase in directive emission is achieved. Capability to control directive emission with organic ENZ films is highly useful in applications requiring bio-compatibility of a fluorophore-embedding medium.

中文翻译：

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具有 epsilon-near-zero 方酸分子膜的聚合物荧光团的定向发射

由于其从单光子源到荧光传感和生物成像的广泛应用领域，增强光致发光发射的方向性引起了人们的关注。利用近零ε（ENZ）介质中的零相位超前是实现定向发射的重要方案。尽管针对基于 ENZ 的定向发射提出了各种设计，但大多数 ENZ 介质仅限于金属等离子体或无机电介质的亚波长结构。在这里，我们介绍了一种放置在聚合物荧光团薄膜顶部的有机 ENZ 薄膜，以展示定向发射。通过利用 P3HT 薄膜中的结构相干性和方酸分子薄膜中的 ENZ 响应，定向发射增加了 42%。