Ultrafast green ion-exchange and short lifetime of efficient (NR4)3SiF7:Mn4+ millimeter-sized single crystal for backlight displays

摘要

Since narrowband red emission and broadband blue excitation, Mn4+-activated fluorides show great promise for white lighting and backlit displays. However, it is a challenge to achieve these phosphors with integrations of high absorption efficiency (AE > 60%), short lifetime (<5 ms) and green synthesis. Here, we report an efficient (AE -60%), fast decaying (4.6 ms) red emission in novel double salt (NR4)(3)SiF7:Mn4+ millimeter-sized single crystal via green H2O-phase volatilization and ultrafast ion-exchange association. Interestingly, its ultrafast ion-exchange as touching in crystal mainly root in the strong ionicity and thin prismatic shape of host evidenced by contrastive synthesis of (NR4)(3)SiF6:Mn4+ millimeter-sized single crystal. Refined contrasts into their crystal structure, luminescence behavior and Mn4+ distribution disclose that (NR4)(3)SiF7:Mn4+ presents higher AE and much weaker quenching in Mn4+ concentration and thermal impact over (NR4)(3)SiF6Mn4+ due to its Mn4+ even heavy distribution and larger transition probability. It also could be deduced that the intrinsic relatively loose framework of (NR4)(3)SiF7 might favor the short lifetime of Mn4+ emission. Using (NR4)(3)SiF7:Mn4+ as red component realizes a W-LED with ultrawide color gamut of 122.8% NTSC. Our findings probably propose a green and simple strategy for designing fast decaying, highly efficient, large-sized single crystal Mn4+-doped fluorides for W-LED applications.

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