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

Abstract

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 (K_0.5Na_0.5)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 ⁴G_5/2 → ⁶H_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 (K_0.5Na_0.5)_0.99Sm_0.01Nb_0.09Zr_0.01O₃ 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.