Silver nanowire networks on textured silicon as low-emissivity coatings for photovoltaic/thermal applications

Abstract

Photovoltaic/thermal (PV/T) conversion can convert part of photons into electricity and simultaneously harvest the remaining solar power into heat, which dramatically improves overall solar conversion efficiency and has been recognized as a promising technique for carbon neutrality. However, the textured structure on the surface of crystalline silicon photovoltaic cells greatly enhances the overall mid-infrared emissivity to 0.8 ∼ 0.9, and current research on PV/T low-emissivity coatings does not address this texture structure. Herein, solar-transparent and infrared-reflective silver nanowire networks were introduced to textured silicon surfaces to suppress mid-infrared emissivity and maintain strong solar absorption. The mid-infrared emissivity of the textured silicon is remarkably reduced from 0.97 to 0.19 after coating the silver nanowire networks, while the solar absorptivity is still maintained at a high level with a weighted solar absorptivity of 0.81. Besides, the above-band-gap photon absorptivity of the silver nanowires coating on texture silicon is 0.84 due to the plasmonic effect of the silver nanowire networks and the light trapping effect of the texture structure. The FDTD simulation confirms the spectral selectivity of silver nanowires coating on texture silicon, and the validated energy balance model captures the solar thermal potential of the silver nanowires coating on texture silicon.