title: Broadband omnidirectional antireflection coatings optimized by genetic algorithm.
abstract: An optimized graded-refractive-index (GRIN) antireflection (AR) coating with broadband and omnidirectional characteristics--as desired for solar cell applications--designed by a genetic algorithm is presented. The optimized three-layer GRIN AR coating consists of a dense TiO2 and two nanoporous SiO2 layers fabricated using oblique-angle deposition. The normal incidence reflectance of the three-layer GRIN AR coating averaged between 400 and 700 nm is 3.9%, which is 37% lower than that of a conventional single-layer Si3N4 coating. Furthermore, measured reflection over the 410-740 nm range and wide incident angles 40 degrees -80 degrees is reduced by 73% in comparison with the single-layer Si3N4 coating, clearly showing enhanced omnidirectionality and broadband characteristics of the optimized three-layer GRIN AR coating.
authors.affiliation: Department of Physics, Applied Physics, and Astronomy, Future Chips Constellation, Rensselaer Polytechnic Institute, Troy, NY 12180, USA.
authors.forename: David J
authors.initials: DJ
authors.lastname: Poxson
authors.forename: Martin F
authors.initials: MF
authors.lastname: Schubert
authors.forename: Frank W
authors.initials: FW
authors.lastname: Mont
authors.forename: E F
authors.initials: EF
authors.lastname: Schubert
authors.forename: Jong Kyu
authors.initials: JK
authors.lastname: Kim