(759e) Scalable Self-Assembly of Nanoparticle Antireflection Coatings

Antireflection coatings on transparent substrates (e.g., glass) are important components for a large number of optical and optoelectronic devices, such as displays, lenses, and photovoltaic panels. Traditional quarter-wavelength antireflection coatings produced by vacuum deposition suffer from high operating and equipment costs, limited material selection, low throughput, and small coating areas. Although some solution processing technologies have been developed to reduce the manufacturing cost and improve the production throughput, many of these techniques involve multiple steps, are limited to single-sided coatings on planar substrates, are not very reproducible over large areas, and/or are not inherently parallel for industry-scale manufacturing. Here we report a simple, inherently parallel, and scalable bottom-up approach for fabricating nanoparticle antireflection coatings on large glass substrates. Negatively charged silica nanoparticles are electrostatically adsorbed onto a surface-functionalized glass substrate with positive surface charges to form a monolayer nanoparticle coating. This innovative technology enables the simultaneous coating of multiple 5-in.-sized glass substrates with high and reproducible qualities. Importantly, we combine experiments with theoretical simulations to address a basic question for monolayer nanoparticle-based antireflection coatings - what is the optimal nanoparticle surface area coverage for best antireflection performance? Surprisingly, the theoretical optimal nanoparticle surface area coverage is found to be ~60% instead of 74% for a close-packed colloidal array. We have demonstrated that this optimal nanoparticle coverage is readily achievable by the current electrostatics-assisted bottom-up technology.