Zhao Xun, Wang Ailin, Gao Sili, Yan Duanting, Guo Wanying, Xu Yingyue, Meng Yanli, Wang Chunliang, Shan Guiye
Center for Advanced optoelectronic Functional Materials Research and Key Laboratory for UV light-Emitting Materials and Technology of Ministry of Education, Northeast Normal University, Changchun, 130024, PR China.
Key Laboratory of Infrared System Detection and Imaging Technology, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai, 200083, PR China.
Sci Rep. 2020 Mar 31;10(1):5710. doi: 10.1038/s41598-020-62563-1.
As a kind of excellent photoluminescent material, carbon quantum dots have been extensively studied in many fields, including biomedical applications and optoelectronic devices. They have been dispersed in polymer matrices to form luminescent films which can be used in LEDs, displays, sensors, etc. Owing to the total internal reflection at the flat polymer/air interfaces, a significant portion of the emitted light are trapped and dissipated. In this paper, we fabricate free standing flexible PVA films with photoluminescent carbon quantum dots embedded in them. We disperse silica microspheres at the film surfaces to couple out the total internal reflection. The effects of sphere densities and diameters on the enhancement of photoluminescence are experimentally investigated with a homemade microscope. The enhancement of fluorescence intensity is as high as 1.83 when the film is fully covered by spheres of 0.86 [Formula: see text]m diameter. It is worth noting that the light extraction originates from rather the scattering of individual spheres than the diffraction of ordered arrays. The mechanism of scattering is confirmed by numerical simulations. The simulated results show that the evanescent wave at the flat PVA/air interface can be effectively scattered out of the film.
作为一种优异的光致发光材料，碳量子点已在包括生物医学应用和光电器件在内的许多领域得到广泛研究。它们已被分散在聚合物基体中以形成可用于发光二极管、显示器、传感器等的发光薄膜。由于在平坦的聚合物/空气界面处的全内反射，很大一部分发射光被捕获并消散。在本文中，我们制备了嵌入有光致发光碳量子点的独立柔性聚乙烯醇（PVA）薄膜。我们在薄膜表面分散二氧化硅微球以耦合出全内反射光。用自制显微镜通过实验研究了微球密度和直径对光致发光增强的影响。当薄膜被直径为0.86 [公式：见原文]m的微球完全覆盖时，荧光强度增强高达1.83。值得注意的是，光提取源于单个微球的散射而非有序阵列的衍射。散射机制通过数值模拟得到证实。模拟结果表明，平坦的PVA/空气界面处的倏逝波可以有效地散射出薄膜。
