A highly efficient, orange light-emitting (K0.5Na0.5)NbO3:Sm3+/Zr4+ lead-free piezoelectric material with superior water resistance behavior

Multifunctional luminescent materials based on rare earth doped ferro-/piezoelectrics have attracted much attention due to their potential applications in novel multifunctional devices. Currently, it remains a challenge to fabricate these materials with high photoluminescence quantum yields, comparable to values obtained for traditional phosphors. Herein, we reported a highly efficient, orange light-emitting material with a superior water resistance behavior based on a (K0.5Na0.5)NbO3 (KNN) matrix co-doped with Sm3+ and Zr4+. The phase structure, composition, photoluminescence properties, thermal quenching and water resistance behavior of the samples were systematically studied. A significantly enhanced orange light-emission at 597 nm originating from the (4)G(5/2) --> H-6(7/2) transition of Sm3+ was observed by the introduction of Zr4+ ions, which can be well explained by the exchange charge model of the crystal field. Particularly we achieve a photoluminescence quantum yield as high as 53% and superior water resistance property almost maintaining the same PL intensity as before immersion after 80 h water immersion time for the composition of (K0.5Na0.5)(0.99)Sm0.01Nb0.09Zr0.01O3 under 407 nm n-UV light excitation. The QY value can be comparable to some commercial phosphors, such as Y2O2S/Y2O3:Eu3+. These findings show the great potential of the Sm3+/Zr4+ co-doped KNN material for future applications in white LEDs and novel multifunctional devices.