Upright nanopyramid structured cover glass with light harvesting and self-cleaning effects for solar cell applications

In this paper, we demonstrate the effect of upright nanopyramid (UNP) structured cover glass with light harvesting and self-cleaning functions on the device performance of monocrystalline Si solar cells. The UNP structures were fabricated on the surface of the glass substrate by simple, high throughput and low cost UV nanoimprint lithography, using a Si master mold with inverted nanopyramid (INP) structures. The diffuse transmittance and haze ratio values were significantly increased for UNP patterned glass, especially in the wavelength range 300–600 nm compared to the bare glass; this implies that antireflection and strong light scattering are due to the UNP structures. By replacing a bare cover glass with UNP patterned glass, the power conversion efficiency of the monocrystalline Si solar cell was substantially enhanced by about 10.97%; this is mainly due to the increased short-circuit current density J _SC of 32.39 mA cm⁻² compared to the reference cell with bare cover glass (i.e. J _SC  =  31.60 mA cm⁻²). In addition, unlike the bare cover glass (i.e. θ _CA ∼ 36°), the fluorinated UNP structured cover glass exhibited a hydrophobic surface with a water contact angle ( θ _CA) of ∼132° and excellent self-cleaning of dust particles by rolling down water droplets. (paper)