Highly transparent all-dielectric metasurface to block the near-infrared region of the solar spectrum

Opt Express. 2020 Oct 12;28(21):30466-30477. doi: 10.1364/OE.403559.

Abstract

Blocking the near-infrared region (NIR) is indispensable for saving energy consumed to maintain the interior temperature in buildings. However, simultaneously enhancing transmission in visible light and blocking in the NIR remains challenging. Here, we theoretically demonstrate a transparent all-dielectric metasurface selectively blocking the NIR by using TiO2 nanocylinders and an indium tin oxide (ITO) layer. The ITO layer is implemented as a back reflector because ITO is transparent in visible light, whereas the ITO becomes a reflective material in the long-wavelength region (λ > 1500 nm). The designed metasurface exhibits high average transmittance of 70% in visible light and high solar energy rejection (SER) of 90% in the NIR. Furthermore, the blocking capability in the NIR of the designed metasurface is maintained over a wide range of an incident angle and polarization angle of light. Therefore, the metasurface gives a guideline for designing energy-saving applications.