Anionic Regulation toward Bi³⁺ Selective Occupation for Full-Spectrum White Light Emission

Area of Science:

• Materials Science
• Solid-state Chemistry
• Luminescence

Background:

• Designing high-quality white light-emitting diode (LED) phosphors requires selective activator occupation within the host material.
• Achieving full-spectrum single-phase white light emission from a single phosphor remains a significant challenge in solid-state lighting.

Purpose of the Study:

• To design and synthesize a novel single-phase white phosphor with enhanced luminescent properties.
• To investigate the effect of selective Bi³⁺ activator occupation in a mixed anionic group host for white light emission.
• To evaluate the thermal stability and color rendering performance of the developed phosphor for white LED applications.

Main Methods:

• A boron phosphate solid-solution phosphor, Na₂Y₂(BO₃)_2-x(PO₄)_x:Bi³⁺ (NYB_2-xP_xO), was synthesized.
• Selective occupation of Bi³⁺ activators in mixed anionic groups (BO₃)^3- and (PO₄)^3- was utilized.
• Photoluminescence spectra, internal quantum efficiency, thermal stability, and color rendering index (CRI) were characterized.

Main Results:

• The synthesized Na₂Y₂(BO₃)_2-x(PO₄)_x:0.005 Bi³⁺ phosphor demonstrated tunable blue-to-white light emission.
• An intense orange-red emission at 590 nm was observed due to Bi³⁺ occupation in Na lattice sites.
• The phosphor exhibited an internal quantum efficiency of 56.42%, excellent thermal stability (94.2% intensity retention after cycles), and a high color rendering index (Ra = 90.8, R9 = 85).

Conclusions:

• The selective occupancy of Bi³⁺ ions in the mixed anionic groups of the Na₂Y₂(BO₃)_2-x(PO₄)_x host is crucial for achieving white light emission.
• The developed NYB_1.5P_0.5O:0.005 Bi³⁺ phosphor shows great potential for high-performance white LEDs due to its spectral properties and stability.
• This study offers a new strategy for designing single-phase phosphors for full-spectrum white light emission.