Effect of the extinction coefficient on the extraction efficiency of ZnS:Mn thin-film phosphors grown on two-dimensional nanorod substrates

Abstract

We have studied the effects of varying the extinction coefficient of two-dimensional (2D) nanorod-assisted ZnS:Mn thin-film phosphors on their photoluminescence extraction efficiency. The finite-difference time-domain method was employed for the design and analysis of 2D nanorod-assisted thin-film phosphors. Using a nanorod pattern with a depth of 200 nm, a lattice constant of 600 nm, and a radius of 180 nm, the extraction efficiency of a transparent ZnS:Mn thin-film phosphor is predicted theoretically to increase by a factor of more than ∼9.1. Experiments have shown that incorporation of the 2D SiO2 nanorod layer only improves the light extraction efficiency over that of a conventional ZnS:Mn thin-film phosphor by a factor of ∼4.0. We discuss the reasons for this mismatch between the theoretical and experimental extraction efficiencies, in order to further improve the extraction efficiency of ZnS-based thin-film phosphors.