Patent ID: 8076846

Claim:
A light-emitting element assembly comprising: (a) a light-emitting element; (b) a sealing member that seals the light-emitting element; and (c) a filling material filled in a space disposed between the light-emitting element and the sealing member, wherein the filling material comprises a nanoparticle-resin composite material in which metal oxide nanoparticles are dispersed in a polymer, the metal oxide nanoparticles including an oxide of a metal selected from the group consisting of zirconium, niobium, indium, tin, cerium, hafnium, and tantalum, wherein the metal oxide nanoparticles are crystalline and have a particle diameter of 1×10 −8 m or less, wherein surfaces of the metal oxide nanoparticles are coated with a surfactant, and wherein the metal oxide nanoparticles are crystallized at a temperature greater than or equal to 200° C. and less than or equal to 400° C.