Mn4+ doped narrowband red phosphors with short fluorescence lifetime and high color stability for fast-response backlight display application

Abstract

Mn4+-activated narrow-band red phosphors are the key materials for wide-gamut displays, however, it is a great challenge to develop the phosphor that adapts to the new requirements of fast response and color stability. Here, red phosphors Cs2B’ScF6:Mn4+ (CB’SFM, B’ = Na, K, Rb and Cs) with short fluorescence lifetime (2.06–4.13 ms) and weak intensity of temperature-sensitive zero phonon line (ZPL) emission have been demonstrated. The phosphors can avoid display tailing phenomenon and color shift under different working temperature. The density functional theory (DFT) calculations show that Mn4+ tends to substitute for Sc3+ and form a Cs+ vacancy (VCs′) for charge compensation, which would cause appropriate local environment distortion of Mn4+, resulting in short PL lifetime as well as weak ZPL emission in Cs2B’ScF6:Mn4+. Furthermore, on the basis of the luminescence kinetics, a modified thermal quenching evaluation model is further proposed to evaluate the thermal stability of the doped phosphor. The w-LED device fabricated with the Cs2KScF6:Mn4+, green phosphor β-Sialon and blue chip can achieve a color gamut above 105% of the National Television System Committee (NTSC) standard value, suggesting red phosphor Cs2KScF6:Mn4+ has potential application in the new generation of fast-response and color stable displays.