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The widespread use of light emitting diode (LED) based devices makes us inevitably exposed to a blue-enriched environment and brings a potential risk to our eyes. Developing a blue-light-blocking filter with narrow absorbing band, so as to only block harmful blue light (415-455 nm) is highly expected. Here, we create a blue-light-blocking film, consisting of a transparent medium embedded with plasmonic nanoparticles (NPs) that selectively absorb harmful blue light. We present the optimal design based on Mie theory by comprehensive scanning of the parametric space for the NPs, and experimentally demonstrate this concept with a blue-light-blocking film made of silver NPs in a polymer matrix by a simple solvothermal method. For the case of the silver NPs content ~ 0.16 wt%, the film can block harmful blue light ~ 65% at λ0 ≈ 430 nm, while maintaining high transparency for the long wavelength light (λ0 > 500 nm). We also demonstrate that it is possible to correct color cast by optimizing the design of the plasmonic NPs with sharp absorption resonances at yellow waveband. This method has attractive features including simplicity, low cost, non-toxic and scalability to large sizes, which makes it beneficial for blue-light-blocking applications.

We report a transparent display based on a metasurface of silver nanoparticles (Ag NPs), consisting of a transparent substrate and a layer of Ag NPs deposited by a dielectric film. The Ag NPs metasurface is prepared by a simple and direct annealing process. It presents a deep transmission valley at the wavelength of λ = 468 nm and enables desired transparent display by projecting the monochromatic image onto the metasurface. We also demonstrate that the formed Ag NPs can be approximated as truncated nanospheres, which have obvious directional scattering properties, and can radiate most of the scattered energy into the backward hemisphere with a relatively large angular beamwidth (the full width at half maximum of the scattered intensity) of ~ 90°. Therefore, the fabricated displays possess wide viewing angles and high brightness characteristics. Additionally, the transmission modes can be red-shifted to the wavelength of λ = 527 nm by controlling the thickness of the deposited dielectric film. This approach using traditional thin film deposition and moderate annealing processing techniques enables simple, low-cost, and scalable fabrication in large areas for the transparent displays.

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