Bioinspired Antireflection Double‐Layer Coatings Design Method and Light Management to Realize Radiative Sky Cooling in Photovoltaic Module

Abstract

Recent research on combining photovoltaic (PV) modules with radiative sky cooling (RSC) technology has elicited much interest. Such cross‐disciplinary technology coupling provides a feasible approach to solar cells’ nighttime applications. However, current commonly used radiative sky cooling materials’ (RSCMs) conflict with the solar light harvesting and utilizing of PV module. The spectral selectivity characteristics of the strong transmission in the solar spectrum range (0.3–1.1 μm) and the enough emissivity within the atmosphere transparency window (8–13 μm) are the essential to develop the PV module‐usable RSC coating. Herein, antireflection (AR) structure optimize method and RSC coating design method are proposed to achieve nighttime RSC capacity with high solar radiation transmission property via the RSCM selection and light management, in the visible, near‐infrared, and midinfrared wavelength range, originating from the subwavelength optical effects of bioinspired AR design. A kind of double‐layer coating consisting of the PDMS substrate layer and SiO2 close‐packed hexagonal rotating parabolic body‐bioinspired moth‐eye structure cover layer is designed in this research. The coating has 0.997 average transmissivity characteristic in solar spectrum and can lower the PV cell temperature over 10.5 K than ambient at night.