Warm-white emitting Dy³⁺ and Eu³⁺ coactivated NaSrY(BO3)2 phosphors for solid-state lighting

Abstract Dy3+ and Eu3+ coactivated NaSrY(BO3)2 phosphors were prepared using a solid-state diffusion method. Singly doped NaSrY(BO3)2: Dy3+ phosphors showed dual emission peaks in the blue and yellow regions of the visible light spectrum, which were insufficient to provide the white light with a desirable color rendering index (CRI) and correlated color temperature (CCT). The absence of the red component was the major reason behind the failure of Dy3+-doped phosphors in producing luminescence with suitable CRI and CCT. This issue was resolved by introducing an appropriate quantity of Eu3+ ions that contributed the red luminescence peaks and compensated for the missing red component in the Dy3+ spectrum. This approach improved the CRI of the phosphors as compared to the singly doped NaSrY(BO3)2: Dy3+ phosphors. Owing to the stable crystal structure of NaSrY(BO3)2, the lanthanide ions were able to successfully incorporate and luminesce in the lattice. By varying the Dy3+/Eu3+ ratio, it was possible to tune the CCT and achieve optimum warm-white emissions with a desirable CCT. With this approach, NaSrY(BO3)2: Dy3+, Eu3+ phosphors produced warm-white light with promising applications in advanced lighting solutions and display devices.