Choi Kyu-Ri, Kim Minjae, Wu Jeong Weon, D'Aléo Anthony, Lee Yeon Ui
Department of Physics, Chungbuk National University, Cheongju, Chungbuk, 28644, South Korea.
Department of Physics, Ewha Womans University, Seoul, 03760, South Korea.
Nanophotonics. 2023 Apr 25;12(13):2471-2478. doi: 10.1515/nanoph-2022-0763. eCollection 2023 Jun.
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.
由于光致发光发射的增强方向性在从单光子源到荧光传感和生物成像等多种应用领域具有广泛应用，因此备受关注。利用近零介电常数（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介质都局限于金属等离子体或无机电介质的亚波长结构。在此，我们介绍一种置于聚合物荧光团薄膜之上的有机ENZ薄膜，以展示定向发射。通过利用聚3-己基噻吩（P3HT）薄膜中的结构相干性和方酸菁分子薄膜中的ENZ响应，实现了42%的定向发射增强。利用有机ENZ薄膜控制定向发射的能力在需要荧光团嵌入介质具有生物相容性的应用中非常有用。
