Self-assembled self-cleaning broadband anti-reflection coatings

Anti-reflection (AR) coatings are widely used in a spectrum of optical and optoelectronic devices, such as monitors, car dashboards, optical lenses, photodiodes, and solar cells. Narrowband quarter-wavelength single-layer and broadband multilayer dielectric AR coatings are typically fabricated by expensive and low-throughput vapor deposition processes (e.g., sputtering). Inspired by the subwavelength-structured cornea of some nocturnal moths, nanostructured broadband moth-eye AR coatings that can significantly suppress optical reflection over a wide range of wavelengths and light incident angles have been extensively exploited by both top-down and bottom-up approaches. Among many available bottom-up technologies, colloidal self-assembly is a promising approach as it is simple, fast, and inexpensive. In this review article, we will discuss two scalable colloidal self-assembly technologies based on Langmuir–Blodgett assembly and spin-coating for fabricating quarter-wavelength and moth-eye AR coatings with unique self-cleaning functionalities on transparent substrates (e.g., glass) and semiconductor wafers (such as crystalline silicon and GaAs).