Comparison of Brightness of Emitting Semiconductor Nanocrystals with That of Rare-Earth Phosphor

Abstract

A method was developed to compare the brightness of newly developed thin films with dispersed photoluminescent CdTe semiconductor nanocrystals (NCs) at an ultimately high concentration (ca. 0.01 M) with that of a typical commercial rareearth phosphor (Y 2 O 2 S:Eu). We have found it is reasonable to compare their brightness under conditions of the same sample thickness, excitation intensity, and wavelength. At the weak-excitation limit, the brightness of the new films was about 30 times higher. This higher brightness is due to the higher concentration and emission efficiency of NCs, and the larger absorption cross section per unit volume of NCs. The difference in the brightness increases with the excitation intensity because rare-earth phosphors exhibit a strong saturation phenomenon due to their long emission decay time. Because these films are efficiently excited by UV-blue diodes, the power of which is steadily increasing, they will become more applicable in future.