Superhydrophobic coatings with high-transparency (i.e., high "specular" transmittance) are key to the development of low-maintenance applications based on glass, such as smart windows, touch panels, see-through displays, LiDARs, and photovoltaics (PVs). We define the term transparency as an optical quantity of being transparent and “haze-free” such that it is distinguished from the amount of light simply passing from one medium to another (i.e., transmittance). Hence, high-transparency surfaces allow light to pass through them with marginal scattering and reflection losses, thereby providing a clear vision. Therefore, they are characterized by low haze and high transmittance, which is a prerequisite for glass-based applications.

We developed a haze-free, antireflective superhydrophobic surface that consists of hierarchically designed nanoparticles. Close-packed, deep-subwavelength-scale colloidal silica nanoparticles and their upper, chain-like fumed silica nanoparticles individually fulfill haze-free broadband antireflection and self-cleaning functions. These double-layered hierarchical surfaces are achieved through a scalable spraying method that allows for precise control over the coating morphology to attain the desired optical and wetting properties. They provide a “specular” visible transmittance of >97% when double-side coated and a record-high self-cleaning capability with a near-zero sliding angle. The developed surfaces can significantly enhance power conversion efficiencies and aid in retaining pristine device performance in a dusty environment through self-cleaning experiments on photovoltaic devices.