(264e) Self-Assembled Nanoparticle Antireflection Coatings on Geometrically Complex Optical Surfaces
Antireflection (AR) coatings are of great technological importance in a wide spectrum of applications ranging from improving conversion efficiencies of solar cells to reducing unwanted light reflection at optical surfaces. However, traditional vacuum deposition technologies suffer from high cost, limited material selection, and low throughput. Critically, it is formidably challenging in coating nonplanar optics with complex geometries, especially those with enclosed concave surfaces. Here we report a simple and scalable electrostatics-assisted colloidal self-assembly technology for fabricating nanoparticle AR coatings on geometrically complex optical surfaces. Surface-functionalized silica nanoparticles with designed surface charge densities can be electrostatically adsorbed on various material surfaces with opposite charges, forming quarter-wavelength AR coatings. Compared with other bottom-up approaches (e.g., layer-by-layer deposition), this single-step, solution-based process enables much simpler and faster assembly of uniform monolayer nanoparticle AR coatings on curved and enclosed optical surfaces. Complementing systematic microstructural and optical characterization, we have also performed numerical simulations to gain fundamental insights into the effects of nanoparticle surface coverage ratio on antireflection performance of self-assembled nanoparticle AR coatings. Importantly, we found that optimal nanoparticle surface coverage predicted by the theoretical model can be readily achieved by this simple bottom-up technology.