YAG：Ce Phosphors for WLED via Nano-Pesudoboehmite Sol-Gel Route

The sub-micron sized YAG ： Ce phosphors were synthesized via a modified sol-gel method by peptizing nano-pesudoboehmite particulate. It is found that YAG phase from the dried gel powders appears at 1000 ℃ then the pure YAG phase exists at a relatively lower sintering temperature of 1400 ℃. The smaller sizes of phosphors in the ranges of 1 - 3 μm are obtained due to the contribution of seeding effects of nano-sized alumina particles to strengthen each step of the processes. Both the excitation and emission spectra of photoluminescence of the phosphor obtained at 1400 ℃ meet well with the spectroscopic requirements of the WLED phosphors.     

A next-generation wide color gamut WLED with improved spectral performance in phosphor composite functional solid

As is well known, a way to obtain a high color resolution and saturation of a liquid crystal display and thereby obtain a higher visual accuracy and comfort in the coming 5G era remains an urgent challenge. In the present study, a new type of phosphor composite material doped with Ln³⁺ ions provides a promising alternative to the color filters used in White light-emitting diodes (WLEDs), achieving a better performance regarding the realization of a wider color gamut. The advantages of this composite material are illustrated through an abundant phase and morphology analysis along with a discussion regarding the X-ray photoelectron spectroscopy of the valence bond of Ce ions, which maintain the luminescence properties of the phosphor while providing a stable and solid amorphous environment. An improved spectral performance was obtained through color filtering at 580 nm along with the regulating effects of red, green, and blue emissions according to the doped Ln³⁺ ions. Notably, we fabricated a high-performance WLED based on a Ln³⁺-doped PiG with a correlated color temperature of 5037 K, color rendering index of 72.8, and high color gamut of 91.97%, providing a new choice for the development of luminescence materials with a high color resolution and saturation.     

基于AP3029的便携式数码产品背光驱动电源的设计与应用

本文阐述了基于电感的白光二极管驱动芯片——AP3029的特点,作为一款PWM升压型DC-DC变换器,AP3029内部集成了功率开关管和肖特基二极管,可以降低系统成本,节省系统空间。由于采用恒流控制方式,有利于降低系统损耗,提高效率。此外,AP3029采用SOT-23-6和TOST-23-6封装形式,内置功能完善的保护电路,是便携式数码产品的理想选择。     

Ce:YAG荧光陶瓷掺杂Gd对白光LED发光性能的影响

Ce: YAG荧光陶瓷具有突出的导热性及化学稳定性, 相比有机硅胶封装法在高功率白光LED的应用上具有更广阔的应用前景。本研究采用真空固相烧结法制备了不同Gd掺杂浓度的(Gd, Y)₃Al₅O₁₂:Ce样品, 通过XRD, SEM及荧光光谱等表征手段, 研究了Gd掺杂对Ce:YAG荧光陶瓷的晶体结构及其用于白光LED时对发光性能的影响。实验表明, 随着Gd掺杂浓度的提高, Gd³⁺取代Y³⁺ 的位置进入晶格, 使得样品的晶格常数增加。Gd³⁺还影响了Ce³⁺对蓝光的吸收, 同时Ce³⁺将蓝光转换成黄光的效率也下降, 导致光效从81.45 lm/W降低至63.70 lm/W。Gd的掺 杂使Ce³⁺的光致发光谱峰位从534 nm向564 nm红移, 显色指数从61.3提升至70.2。Gd的掺杂虽然降低了发光 效率, 但显著提高了(Gd, Y)₃Al₅O₁₂:Ce样品的显色指数, 使得黄色YAG荧光陶瓷应用于白光LED的性能得到了 提高。     

A novel bifunctional Dy3+ activated RbCaF3 single phase phosphor: Facile synthesis and dual-luminescence properties for WLEDs and dosimetry applications

A series of Dy³⁺ activated RbCaF₃ phosphors was synthesized by the conventional high temperature solid state reaction technique under ambient atmosphere. The structural properties and morphology of synthesized compounds were analyzed by PXRD and FE-SEM, respectively. The chemical composition of synthesized phosphors was obtained by EDAX. The phosphor was excited at 386 nm and monitored at 484 and 574 nm, and the strongest peak was located at 484 nm (blue region). In addition, the point of RbCaF₃:Dy³⁺ with calculated chromaticity coordinates in the CIE diagram was located in the yellow region. TL characteristics of the RbCaF₃:Dy³⁺ phosphor was analyzed and the glow curve peak was emitted at 355 K. The symmetry factor, Balarin parameter, activation energy and frequency factor were calculated by Chen method from the TL glow curve, and the TL signal degradation was also analyzed.     

A novel single-phased white light emitting phosphor with single Eu2+ doped whitlockite structure

Exploring novel efficient single-phased full spectrum phosphor with individual activator doping for white light emitting diodes is highly significative and benefit for scientific activities. Herein, by designing and modifying the β-Ca₃(PO₄)₂-type structure, the Ca₁₉MgNa₂(PO₄)₁₄: Eu²⁺ (CMNP) phosphor was proposed as a single-phased full spectrum white phosphor. The phase purity and clear crystal structure were then determined by employing the Rietveld refinement and energy dispersive X-ray spectroscopy. PLE and PL spectra indicated CMNP: xEu²⁺ (0.1% ≤ x ≤ 1.0%) phosphors could be well fitted with 365 nm LED chip and exhibited a full spectrum emission band covering all visible lights of 400–750 nm belonging to the 5d?4f transitions of Eu²⁺. Further, the selective occupation of Eu²⁺ ions in different cation sites and luminescence kinetics depending on the Eu²⁺ dopants were characterized by theoretical calculation, Rietveld refinement results and decay curves. Finally, the WLED device fabricated by (near)-UV WLED chip and CMNP: 0.75 %Eu²⁺ phosphor could present excellent color temperature (6643 K) and CIE coordinate (0.308, 0.346). The current work manifests that Ca₁₉MgNa₂(PO₄)₁₄: Eu²⁺ had excellent luminescent property, which could be used in optical applications.     

WLED照明应急控制电路的设计

本文设计了一种宽范围输入的白光LED（WLED）恒流控制电路,内置锂电池应急照明模块,并具有对电池自动充电、应急自启动以及恒流供电等功能,实验证明控制电路所需各项性能指标均较好地实现。     

白光LED用Ce:YAG单晶光学性能及封装工艺的研究

采用提拉法生长了白光LED用Ce:YAG单晶, 通过吸收光谱、激发发射光谱和变温光谱对其光学性能和热稳定性进行了表征, 并研究了晶片用于封装白光LED光源中各因素对其光电性能的影响。Ce:YAG晶片能被466 nm波长的蓝光有效激发, 产生500~700 nm范围内的宽发射带。Ce³⁺的4f→5d轨道的跃迁吸收对应于202、219、247.3、347.4和455.5 nm五个吸收峰, 据此量化分裂的5d能级能量, 依次为21954、29154、40437、45662和49505 cm^-1。温度升高, Ce³⁺的²F_7/2能量升高导致了发光强度的降低, 可降低幅度(13.28%)不大, 比肩国家标准且要优于目前商用白光光源的Ce:YAG单晶制白光LED光源的封装工艺, 从芯片、驱动电流、晶片厚度和添加物四方面进行讨论。研究结果表明, Ce:YAG单晶是一种新型白光LED用荧光材料。     

白光LED照明控制技术应用研究

随着LED技术的不断发展,白光LED也逐步应用于室内照明。设计了一种LED驱动控制系统。并与DALI技术相结合,可充分发挥LED的特点,将之高效地应用于室内照明。以提高其系统性能和照明品质。     

基于量子点的白光二极管的研究进展

量子点又称为纳米晶,是一种由Ⅱ-Ⅵ族或Ⅲ-Ⅴ族元素组成的纳米颗粒(粒径1～10nm),由于电子和空穴的量子限域效应,连续的能带结构变成分立的能级结构,受激后可以发射荧光。量子点的发光光谱可以通过量子点的粒径大小来调节。文章基于量子点的电致发光和光致发光的机理,主要介绍了近年来基于量子点的白光发光二极管的研究进展。