Miranda-Muñoz José M, Viaña José M, Calvo Mauricio E, Lozano Gabriel, Míguez Hernán
Instituto de Ciencias de Materiales de Sevilla (Consejo Superior de Investigaciones Científicas-Universidad de Sevilla), C/Américo Vespucio, 49, Sevilla, 41092, Spain.
Mater Horiz. 2024 Nov 11;11(22):5722-5731. doi: 10.1039/d4mh00826j.
Herein, we demonstrate mechanically stable large-area thin films with a purely real refractive index () close to 1 in the optical range. At specific wavelengths, it can reach values as small as = 1.02, the lowest reported for thin solid slabs. These are made of a random network of interwoven spherical silica shells, created by chemical vapour deposition of a thin layer of silica on the surface of randomly packed monodisperse polymer nanoparticles that form a film. Thermal processing of the composites results in highly porous silica-based transparent thin films. We demonstrate the potential of this approach by making novel photonic materials such as strong optical diffusers, built by integrating scattering centers within the ultralow transparent films, or highly efficient light-emitting slabs, in which losses by total internal reflection are practically absent as a result of the almost null optical impedance at the film-air interface.
在此，我们展示了在光学范围内具有接近1的纯实折射率（）且机械稳定的大面积薄膜。在特定波长下，其值可低至 = 1.02，这是薄固体平板所报道的最低值。这些薄膜由交织的球形二氧化硅壳的随机网络构成，通过在形成薄膜的随机堆积的单分散聚合物纳米颗粒表面化学气相沉积一层二氧化硅来制备。对复合材料进行热处理可得到高度多孔的二氧化硅基透明薄膜。我们通过制造新型光子材料来展示这种方法的潜力，例如通过在超低透明薄膜内集成散射中心构建的强光学漫射器，或高效发光平板，在这种平板中，由于薄膜 - 空气界面处的光阻抗几乎为零，几乎不存在全内反射损耗。
