Enhanced absorption of Sr₃Lu₂(BO₃)₄:Ce³⁺,Tb³⁺ phosphor with energy transfer for UV-pumped white LEDs

A series green emission phosphors Sr₃Lu₂(BO₃)₄:Ce³⁺,Tb³⁺ (denoted as SLBO:Ce³⁺,Tb³⁺) with broad absorption band matching well with UV LED chip were synthesized by the solid–state reaction method. The phase and structure were analyzed with XRD, EDX, FT-IR measurements. The energy transfer between Ce³⁺ and Tb³⁺ in SLBO was proved by spectra and decay curves detailedly. The emission colors vary from blue to green by adjusting the ratio of Ce³⁺/Tb³⁺ doped concentration. With temperature increasing, SLBO:Ce³⁺,Tb³⁺ phosphor shows well thermal stability that emission intensity retains 70% of its initial at 25 °C even temperature rising to 150 °C. The internal and external quantum efficiency of SLBO:3%Ce³⁺,8%Tb³⁺ are 77.5% and 34.8% under 340 nm excitation, respectively. Combining the as-synthesized SLBO:Ce³⁺,Tb³⁺ and red emission phosphor CaAlSiN₃:Eu²⁺ coated on a 365 nm UV chip, a warm white LEDs device with CRI of 83 was achieved. All the results indicate that the SLBO:Ce³⁺,Tb³⁺ phosphor has potential application in UV pumped white LEDs.