Phosphor conversion for WLEDs: YBO₃: Ce³⁺, Tb³⁺ and its effects on the luminous intensity and chromatic properties of dual-layer WLED model

Yttrium borate phosphor co-doping Ce³⁺, Tb³⁺ ions (YBO₃: Ce³⁺, Tb³⁺) is fabricated using solid state reaction, and then its luminescence is investigated through the computational energy transfer process. Under excited near-UV light, this YBO₃: Ce³⁺, Tb³⁺ phosphor exhibits strong absorption with broad and sharp emission bands due to the 4f – 5d and 5d – 4f transitions of Ce³⁺ ions and the 4f – 4f transition of Tb³⁺ ions, respectively. The phosphor's emission chromaticity could be tunable by adjusting the concentration of doping ions. With 15% Tb³⁺ and 3% Ce³⁺ in the composition, the phosphor can gain maximum 76.7% external quantum efficacy. The phosphor is proposed for utilization in the phosphor package of white light-emitting diodes (WLEDs) to enhance their lighting performances. The findings point out that by modifying YBO₃: Ce³⁺, Tb³⁺ concentration (5% – 10%), improvements in luminous intensities, color consistency, and color rendering indices can be observed. The higher concentration (10%) of YBO₃: Ce³⁺, Tb³⁺ is more advantageous to the luminous flux and chromatic uniformity in cases of 4000 K and 5000 K WLEDs, while lower (5%) concentration greatly benefits those properties in the case of 3000 K WLED. Regardless of CCTs, the WLEDs show a reduction in chromatic reproduction efficiency with the increasing concentration of YBO₃: Ce³⁺, Tb³⁺. Hence, this green phosphor could be a good material for high-luminescence WLED, yet the modification of phosphor concentration is advisable if the simultaneous good chromaticity is desired.