Highly efficient and thermally stable narrow-band cyan-emitting aluminum oxynitride phosphor for WLEDs and FEDs

Abstract

For the extension of the color gamut of filed-emission displays (FEDs) and realizing the narrow-band emission with the broad excitation band, Eu2+ activated aluminum Oxy-nitride, Al9O3N7:Eu2+, was successfully synthesized through the gas pressure sintering. Based on the host lattice of AlN, the new phase of Al9O3N7 can be produced with the introduction of oxygen. Under the high temperature and pressure, O2− ions partially replace the N3− ions and face-/edge- shared Al(O, N)4 tetrahedron are observed in Al9O3N7 through the Rietveld refinement, which builds the compact host lattice. The TEM and SEM image further shows the change of crystal structure and morphology induced by the introduction of the oxygen. Compared with the blue light emission of AlN: Eu2+, Al9O3N7: Eu2+ emits a bright cyan light peaked at 482 nm with FWHM = 67 nm. The broad excitation band ranges from 300 nm to 415 nm with the maximum at 370 nm, which implies that the Al9O3N7: Eu2+ phosphor is well matched with the NUV - LED chips. Moreover, Al9O3N7: Eu2+ exhibits high quantum efficiency (65%) and excellent thermal stability. The bright cathodoluminescence (CL) emission of Al9O3N7: Eu2+ with excellent stability was detected. The results indicate that this kind of aluminum oxy-nitride with the tight crystal structure enriches WLEDs and FEDs used phosphors.