Study on the structure, energy transfer, and color-tunable photoluminescence of the stable BaY2Si3O10: Bi/Tb/Sm phosphors

Abstract

With the growing concern about energy consumption, white light-emitting diodes(wLEDs), as the fourth generation of lighting sources, are highly scrutinized by researchers. A series of Bi³⁺/Tb³⁺/Sm³⁺ (co)doped BaY₂Si₃O₁₀ phosphors were prepared by traditional solid-state method, and the phase purity was analyzed by X-ray diffraction. In this work, Bi³⁺/Tb³⁺/Sm³⁺ theoretically occupies the Ba/Y sites, and this conjecture is also proved by spectral analysis. Under near ultraviolet (nUV) light excitation, Bi³⁺/Tb³⁺/Sm³⁺ is respectively used as the blue (³P₁ → ¹S₀)/green (⁵D₄ → ⁷F_j)/red (⁴G_5/2 → ⁶H_j) luminescence center. Due to the energy transfer (ET) efficiency between Bi³⁺/Sm³⁺ is not ideal, Tb³⁺ is introduced as a bridge to improve the ET efficiency of the whole system to achieve spectral tunability and application in wLEDs. And at different excitation wavelengths, Bi³⁺ emits a wide range of blue to cyan light because it occupies two cation sites. We selected a proper excitation wavelength and obtained an emission spectrum covering the whole visible region. The CIE color coordinates (0.3487, 0.3313), the correlated color temperature (CCT, 4773.61 K), quantum efficiency (QE, 47.62 %), and thermal stability (T₅₀ = 537 K) of BaY₂Si₃O₁₀: Bi³⁺/Tb³⁺/Sm³⁺ are discussed in depth, Lu³⁺ was used instead of Y³⁺ to improve the thermal stability of BYS. Its excellent luminescence performance indicates that this phosphor has potential applications in nUV wLEDs.