Bio inspired hierarchical photonic nanostructures for anti reflective and self cleaning applications

Abstract

Synthetic superhydrophobic (SH) surfaces with distinct wettability and newlineversatility have found particular attention in both fundamental research and newlineindustrial applications. The superhydrophobicity is a physico-chemical phenomenon newlinecomprising the key parameters, surface architecture and surface chemistry. newlineIn principle, biomimetic SH coating is achieved in two ways: introducing newlinehierarchical nanostructures (HNs) on the hydrophobic surface having a low newlinesurface free energy; or modifying the former HNs with hydrophobic layer newlinehaving a low surface energy (SE). The intermolecular interactions between the newlinecontacting liquids and solid surface play a significant role in determining the newlineCassie-Baxter regime. In addition to superhydrophobicity, self-cleaning coatings newlinewith high transparency are extremely significant for solar panels, window newlineglasses and in opto-electronic devices. Unfortunately, superhydrophobicity and newlinetransparency are conflicting properties in regards to surface roughness. When newlinemicro/nanostructures are present on the surface, transparency of the coating is newlineachieved with minimal scattering loss, especially if the surface roughness is newlinesmaller than the incident light wavelength. However, decreasing the surface newlineroughness reduces the SH properties. The other technical problem is that newlineincreasing the surface roughness leads to Mie-scattering, particularly, if surface newlineroughness exceeds the wavelength of incident light. Thus, the degree of surface newlineroughness should be carefully controlled to fabricate highly transparent SH newlinecoating. Although many reports exist in literature on highly transparent newlineself-cleaning SH coatings, there are many drawbacks on the preparation methods newlinewhich involve special techniques or complicated methodology that are only newlinesuitable for laboratory scale. newline newline