Highly efficient blue-green dual-narrow-emission in RbAl11O17:Eu2+,Mn2+ toward wide-color-gamut human-centric backlights

Abstract

A combination of violet light-emitting diode (LED) chips and trichromatic highly efficient narrow-band emission phosphors to create color images can help to effectively address sleep and mood disorders caused by strong blue LED radiation, and is in line with the development of “human-centric” backlight displays. In this work, RbAl₁₁O₁₇:Eu²⁺ exhibits narrow-band (full width at half maximum = 50 nm), thermally stable (150 °C, 86.96%), and highly efficient blue emission (62.87%) under violet excitation. Rb_0.80Al₁₁O₁₇:Eu²⁺ offers higher color purity than BaMgAl₁₀O₁₇:Eu²⁺ and is an alternative to blue chips. RbAl_10.70O₁₇:0.30Mn²⁺ exhibits narrow green emission (full width at half maximum = 26 nm) and low luminescence efficiency (∼2.91%). An efficient energy transfer of Eu²⁺ → Mn²⁺ in the RbAl₁₁O₁₇:Eu²⁺,Mn²⁺ system is designed for the spectral transition from blue emission to blue-green dual emission. The luminescence efficiencies of Rb_0.80Al_10.95O₁₇:0.20Eu²⁺,0.05Mn²⁺ and Rb_0.80Al_10.80O₁₇:0.20Eu²⁺,0.20Mn²⁺ can reach more than 60%. The good color gamut (118% National Television Standards Committee) of white LEDs encapsulated with a combination of Rb_0.80Al_10.95O₁₇:0.20Eu²⁺,0.05Mn²⁺, K₂SiF₆:Mn⁴⁺ phosphors and a violet chip justifies their potential application in human-centric backlit displays. The guidance on the modulation of the excitation spectrum and enhancement of the luminescence performance of Mn²⁺-doped phosphors is provided in this work.