A thermally stable narrow-band green-emitting phosphor MgAl2O4:Mn2+ for wide color gamut backlight display application

Abstract

The discovery of stable narrow-band green emitting phosphor suitable for blue InGaN chip excitation is crucial to improve the color gamut of the phosphor converted backlighting device. However, it is a great challenge. Herein, a Mn²⁺ activated thermally stable narrow-band green emitting phosphor MgAl₂O₄:Mn²⁺ peaking at 525 nm with a full-width at half-maximum (FWHM) of 35 nm and a quantum efficiency of 45% upon 450 nm blue-light excitation is demonstrated. This phosphor does not exhibit thermal quenching even up to 300 °C (109.5%@300 °C of the integrated emission intensity at 23 °C) due to the high rigidity of the host MgAl₂O₄. Using the as-synthesized optimized phosphor Mg_0.95Al₂O₄:0.05Mn²⁺ as the green light component, and a commercial phosphor K₂SiF₆:Mn⁴⁺ as the red one, an InGaN chip excited white LED device with a color gamut of 116% National Television System Committee (NTSC) standard is obtained. Furthermore, by applying the fabricated LED device for backlights in a liquid crystal display (LCD) TV, a more colorful frame can be realized compared to when commercial LED backlights are used, suggesting that the Mn²⁺ ion based green emitting phosphor has great potential for application as LCD backlights.