Enhanced extraction efficiency of Y2O3:Eu3+ thin-film phosphors coated with hexagonally close-packed polystyrene nanosphere monolayers

A hexagonally close-packed, two-dimensional (2D) polystyrene (PS) nanosphere photonic crystal (PC) monolayer was built on a sol-gel derived Y2O3:Eu3+ thin film in an attempt to improve the efficiency of light extraction from the phosphor side of the Y2O3 : Eu3+ thin film. The effects of crystallinity and particle size of the 2D PS nanosphere/air PC layer on the extraction efficiencies of the Y2O3 : Eu3+ thin-film phosphors were investigated. The integrated photoluminescence extraction was improved by a factor of over 3.7 compared to that of a conventional Y2O3 : Eu3+ thin film, by adding a 2D PS monolayer array of 580 nm sized nanospheres with high crystallinity.