Hierarchical structured polymers for light-absorption enhancement of silicon-based solar power systems

Abstract

Light-absorption enhancement of silicon (Si)-based solar power systems (i.e., solar modules) is reported by employing a ultraviolet-curable polymer (i.e., NOA63) film integrated with a hierarchical structure (HS) consisting of nanonipples on micropyramids onto the PET cover as a protective antireflection (PAR) layer. The HS-patterns can be easily transferred from Si molds with the HS via poly-dimethylsiloxane stamps by soft lithography. The HS-NOA63 film increases the total and diffuse transmittances of the bare polyethylene terephthalate (PET), simultaneously, at wavelengths of 380–1100 nm, thus resulting in the reduced surface reflection (i.e., lower solar weighted reflectance (R_sw) of 6.1%) and the strong light scattering (i.e., much higher average haze ratio (H_avg) of 90.7%) compared to the bare PET (i.e., R_sw = 11.7% and H_avg = 6.9%). Consequently, the Si solar modules with the HS-NOA63 PAR layer of the PET cover exhibit a superior solar power generation in a wide incident angle range (0–70°) of solar irradiance, especially, showing a relative increment percentage of 6.3% in power conversion efficiency (PCE) at 0° (i.e., from PCE = 13.46 to 14.3%). Also, it has a superhydrophobic surface with a high water contact angle of 150°, which leads to a self-cleaning ability to protect Si solar modules from being polluted by water droplets and dust particles in outdoor applications.