目前, 高效窄带荧光粉的研发对于白光发光二极管(WLED)向高性能液晶显示器背光源的应用至关重要. 本工作采用高温固相法制备了一种高效窄带蓝色荧光粉Ba₃Y₂B₆O₁₅:Bi³⁺, 并对其结构和性能进行了表征和计算. 计算表明, Ba₃Y₂B₆O₁₅的带隙较宽, 为4.67 eV, 宽的带隙为高效率荧光粉提供了保障. Ba₃Y₂B₆O₁₅:0.5%Bi³⁺ (0.5%为摩尔分数)的发射光谱峰值在409 nm, 半峰宽仅为2168 cm⁻¹ (36.2 nm), 属于窄带蓝光发射. Ba₃Y₂B₆O₁₅:0.5%Bi³⁺的内量子效率高达93.8%, 色纯度也高达98.9%, 其热稳定性能也较好, 在150 ℃时的发光强度是室温发光强度的73.9%, 且几乎没有色漂移. 当Y被Sc部分取代时, Ba₃Sc_xY_2-xB₆O₁₅:Bi³⁺(0≤x≤1.6)的发射光谱随着x的增大而发生红移. 最终, 将蓝色荧光粉Ba₃Y₂B₆O₁₅:0.5%Bi³⁺与商品化的红绿两种荧光粉混合均匀后涂在365 nm的芯片上制成WLED, 在20 mA的电流驱动下, 得到的WLED相关色温为5679 K, 色域可达95.3% NTSC((美国)国家电视标准委员会).

At present, the development of efficient (high quantum efficiency and high thermal stability) narrow-band emitting phosphors is a crucial problem in the application of white light emitting diodes (WLED) for high-performance liquid crystal display (LCD) backlights. In this work, an efficient narrow-band blue emitting phosphor Ba₃Y₂B₆O₁₅:Bi³⁺ was prepared by high temperature solid state method, and its structure and properties were characterized and calculated. By using the density functional theory (DFT), Ba₃Y₂B₆O₁₅ is calculated to be a direct band gap material with a high band gap value of 4.67 eV, which is a necessary condition for achieving high quantum efficiency phosphors. The experiment results show that Ba₃Y₂B₆O₁₅:0.5%Bi³⁺ has a narrow-band blue-emitting spectrum with a full width at half maximum (FWHM) of 2168 cm⁻¹ (36.2 nm) at 409 nm, which is owing to the ³P₁→¹S₀ transition of Bi³⁺ ions. The emission spectra of Ba₃Y₂B₆O₁₅:0.5%Bi³⁺ can be split into two peaks at 406 and 422 nm, respectively, because there are two kinds of Y ions (Y1 and Y2) in the crystal cell of Ba₃Y₂B₆O₁₅. Under the 365 nm UV radiation, the Ba₃Y₂B₆O₁₅:0.5%Bi³⁺ exhibits high internal quantum efficiency (IQE=93.8%), and ultra-high color purity (98.9%). The high quantum efficiency and narrow-band emission spectrum are mainly due to the compact and highly symmetric crystal structure of Ba₃Y₂B₆O₁₅ matrix. The photoluminescence (PL) intensity of Ba₃Y₂B₆O₁₅:0.5%Bi³⁺ remains 73.9% of the initial intensity at 150 ℃, and there is almost no color drift. The thermal quenching activation energy (E_a) of Ba₃Y₂B₆O₁₅:0.5%Bi³⁺ was calculated to be 0.290 eV by the Arrhenius Equation, which indicates that Ba₃Y₂B₆O₁₅:0.5%Bi³⁺ has high thermal stability. When Y³⁺ is partially substituted by Sc³⁺, the emission spectrum of Ba₃Sc_xY_2-xB₆O₁₅:Bi³⁺ (0≤x≤1.6) is redshifted with the increase of x. Finally, the blue phosphor Ba₃Y₂B₆O₁₅:0.5%Bi³⁺ was mixed with commecial green and red phosphors and then coated them on a 365 nm chip to fabricate a WLED device. Under a driven current of 20 mA, the correlated color temperature of the obtained WLED is 5679 K and the color gamut can reach 95.3% NTSC. Above results indicate that Ba₃Y₂B₆O₁₅:Bi³⁺ is a promising phosphor for high-performance LCD backlights.