白光LED用光转换材料的研究

白光LED是新型的固体照明光源,具有耗电量小、寿命长、环保、响应速度快等优点.主要介绍了与白光LED相匹配的光转换材料的种类及每种光转换材料的研究进展,并比较了其优缺点.单一基质白光荧光粉因颜色稳定、色彩还原性好,成为白光LED用光转换材料的研究热点,此外由于近紫外LED芯片的研究也比较活跃,所以目前对于单一基质白光荧光粉的研究多是基于近紫外芯片激发.随着研究的深入,近紫外LED与单一基质白光荧光粉相匹配实现白光发射有望成为白光LED产业化的主体.     

硼酸盐体系单一基质白光LED荧光粉的研究进展

白光发光二极管(LED)具有低能耗、高效率、长寿命和无汞污染等优点,被誉为新一代固体照明光源。紫外-紫外光激发的白光LED用单一基质白光荧光粉具有独特优势,成为白光LED的研究热点。主要探讨了硼酸盐体系单一基质的白LED光荧光粉的研究进展。     

蓝光激发红色荧光粉的研究进展及其在白光LED中的应用

蓝光LED芯片激发黄色荧光粉是目前白光LED的主要实现方式,引入红色荧光粉对调整白光LED的显色指数及色温有重要意义。重点介绍和评述了可被蓝光激发且具有宽发射带的硫化物、氮化物、铝酸盐等几种体系红色荧光粉的发光性质、最新研究成果及在白光LED中的应用。对比发现,氮化物荧光粉可被从近紫外到可见绿光有效激发,随基质组成的不同,可发出峰值波长为600～650nm的红色荧光,且由于其优良的化学稳定性、热稳定性成为最有前途的一类红色荧光粉。采用两种以上的荧光粉代替单一黄色荧光粉,有利于调整白光LED的色温,提高显色指数。     

白色发光二极管用蓝色荧光粉的研究进展

白色发光二极管(WLED)被称为第四代照明光源,应用前景十分广阔.概速了目前国内外WLED用蓝色荧光粉的研究进展,介绍了WLED用蓝色荧光粉的基质材料、制备方法、发光中心和掺杂离子等对WLED用蓝色荧光粉发光性能的影响,展望了该类荧光材料的发展研究趋势和应用前景.     

近紫外光激发的白光LED用单基质硅酸盐荧光粉的研究进展

白光LED被称作第4代照明光源,有着庞大的应用市场.荧光粉光转换白光LED是当今固态照明的主流方案.研制近紫外光激发的白光LED用单基质硅酸盐荧光粉具有十分重要的意义.综述了目前国内外这一领域的研究进展,并指出了当前存在的问题及未来的发展方向.     

白光LED用单一基质白光荧光粉的研究进展

白光LED以其独特优势被称为第四代光源,具有广阔的应用前景。单一基质白光荧光粉(SMWP)因颜色稳定、色彩还原性好,成为白光LED用光转换材料的研究热点。概述了由近紫外LED芯片激发的白光荧光粉的研究现状,指出了该荧光粉存在的问题并对其发展趋势做了展望。     

白光LED用红色荧光粉的研究进展

白光LED具有工作电压低、功耗低、可靠性高、使用寿命长、环境友好和高能效等一系列优点,是未来照明光源的发展方向。利用LED技术实现白光的方法主要有3种,其中采用蓝光、紫光及近紫外LED芯片激发红、绿、蓝等三基色或多基色荧光粉得到白光LED的技术具有成本低、显色性好等优势,是白光LED的主要发展方向。红色荧光粉在调制白光的色温及改善其显色性等方面起重要作用,其制备技术是目前制约白光LED大规模应用的关键技术,亟待解决。详细介绍了白光LED用红色荧光粉的十余个主要材料体系的发光性能、基本制备方法、取得的研发进展,简单探讨了其未来发展趋势。     

白光LED用红色荧光粉的研究进展

白光LED具有低压、低功耗、高可靠性和长寿命等一系列优点,是一种符合节能环保的绿色照明光源.现阶段的白光LED显色指数低、色温较高,限制了白光LED在室内照明等领域的发展,而红色荧光粉能对白光LED的显色指数的提高及色温的改善影响极其显著.主要介绍白光LED用红色荧光粉几大主要体系的发光性质及最新发展现状.     

白光LED用红色荧光粉的研究与分析

红色荧光粉对白光LED的色温、显色性以及发光效率等关键性能指标有很大的影响。对目前白光LED用红色荧光粉8个主要体系的研究情况进行了详细的介绍与分析。并对比了各个体系红色荧光粉的激发和发射波长、量子效率及色坐标等性能参数。另外,为了更好地对比实验样品和工业产品,还测试和分析了两种工业常用红色荧光粉的激发和发射光谱。指出了红色荧光粉研究及应用过程中存在的激发波长与蓝光芯片的发射波长不匹配、激发效率低、发射光谱范围窄以及其基质与当前所用黄色荧光粉的基质不匹配等问题,最后针对这些问题提出了几点解决建议。     

高效暖白光LED用红光荧光粉研究获进展

正白光L ED由于其节能、环保以及长寿命等特点成为下一代照明器件。目前,商品化的白光L ED主要采用蓝光芯片激发3+YAG:Ce黄光荧光粉,芯片发出的蓝光与荧光粉发射的黄光混合形成白光。但是,3+YAG:Ce荧光粉的发射光谱中红光组份不3+足,采用单一Y AG:Ce荧光粉较难获得低色温(C orrelated Color Temperature,CCT4500K)、高显色指数(Color Rendering Index,CRI80)的暖白光器件,导致了其在室内通用照明中应用的局限性。为解决     

LED用绿色荧光粉的研究进展

白光LED被誉为第四代照明光源,有着显著的节能前景和庞大的应用市场。荧光粉光转换型是未来白光LED发展的主流方向。(近)紫外激发三基色荧光粉的研制具有十分重要的意义。综述了近年来半导体白色发光二极管(WLED)用绿色荧光粉的研究进展,重点推介了性能较好的绿色荧光粉,并展望了LED用绿色荧光粉发展趋势。     

Nano Wave Plates Structuring and Index Matching in Transparent Hydroxyapatite-YAG: Ce Composite Ceramics for High Luminous Efficiency White Light-Emitting Diodes

Replacing traditional luminous silicone or resins with phosphor in ceramics (PiCs) as color converters has been proposed as an efficient way to improve thermal stability of high-power white light-emitting diodes (WLEDs). However, excessive light scattering in existing PiCs results in enormous phosphor-converted light losses, which makes the luminosity of current PiCs color converters less efficient and means that they can only be used in devices working in reflective mode. By introducing nano wave plate structuring and Rayleigh scattering, luminous hydroxyapatite (HA)-YAG: Ce ceramics are prepared from mesoporous HA nanorods and YAG: Ce phosphors at 850 °C, enabling for the first time WLEDs equipped with PiC color converters in transmission mode. With low-temperature sintering and a highly transparent matrix, the quantum yield of HA-YAG: Ce retains ≈90% of the raw phosphor, and WLEDs with the color converters exhibit a record luminous efficiency of 170 lm W⁻¹ and a correlated color temperature below 4500 K. A facile and practical strategy of using nano structural modulation to eliminate birefringence-induced light scattering for fabricating high-performance ceramic converters suitable for multiple mode luminaires is demonstrated.     

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。     

The thermal stability performances of the color rendering index of white light emitting diodes with the red quantum dots encapsulation

Red phosphors are the traditional material used to improve the color rendering index (CRI) of white light emitting diode (WLEDs). In this paper, red quantum dots (QDs) were fabricated and coated on the blue LED chip to replace the red phosphors. By comparing the thermal performances of the CRI for the two WLEDs, we found that WLEDs with the encapsulation of yellow phosphors and red QDs exhibited higher CRI and lower sensitivity to temperature than those with the encapsulation of yellow and red phosphors. The CRI of WLEDs with yellow phosphors and red QDs was 90.9, and its range ability was only 0.3 when the environment temperature changed from 25 °C to 100 °C, while the CRI of WLEDs with yellow and red phosphors was as low as 81.8, and the change of CRI was 2.2 during the same temperature variation.     

智能优化平台的并行实现及在光学设计中的应用研究

构建了一个智能优化平台,包括粒子群算法、蚁群算法、遗传算法、模拟退火算法、混沌算法和复合形法。该平台包括4个模块,分别是优化问题选择,优化参数设置,优化过程显示以及优化结果输出。将该优化平台应用在RGB LED混合白光的优化设计中,对混合照明模块中发光效率和显色指数进行优化,给出了混合照明模块中发光效率和显色指数的计算方法。     

Semiconductor‐Nanocrystals‐Based White Light‐Emitting Diodes

In response to the demands for energy and the concerns of global warming and climate change, energy efficient and environmentally friendly solid‐state lighting, such as white light‐emitting diodes (WLEDs), is considered to be the most promising and suitable light source. Because of their small size, high efficiency, and long lifetime, WLEDs based on colloidal semiconductor nanocrystals (or quantum dots) are emerging as a completely new technology platform for the development of flat‐panel displays and solid‐state lighting, exhibiting the potential to replace the conventionally used incandescent and fluorescent lamps. This replacement can cut the ever‐increasing level of energy consumption, solve the problem of rapidly depleting fossil fuel reserves, and improve the quality of the global environment. In this review, the recent progress in semiconductor‐nanocrystals‐based WLEDs is highlighted, the different approaches for generating white light are compared, and the benefits and challenges of the solid‐state lighting technology are discussed.     

Eu3+, Sm3+ Deep‐Red Phosphors as Novel Materials for White Light‐Emitting Diodes and Simultaneous Performance Enhancement of Organic–Inorganic Perovskite Solar Cells

The luminous efficiency of inorganic white light‐emitting diodes, to be used by the next generation as light initiators, is continuously progressing and is an emerging interest for researchers. However, low color‐rendering index (Ra), high correlated color temperature (CCT), and poor stability limit its wider application. Herein, it is reported that Sm³⁺‐ and Eu³⁺‐doped calcium scandate (CaSc₂O₄ (CSO)) are an emerging deep‐red‐emitting material with promising light absorption, enhanced emission properties, and excellent thermal stability that make it a promising candidate with potential applications in emission display, solid‐state white lighting, and the device performance of perovskite solar cells (PSCs). The average crystal structures of Sm³⁺‐doped CSO are studied by synchrotron X‐ray data that correspond to an extremely rigid host structure. Samarium ion is incorporated as a sensitizer that enhances the emission intensity up to 30%, with a high color purity of 88.9% with a 6% increment. The impacts of hosting the sensitizer are studied by quantifying the lifetime curves. The CaSc₂O₄:0.15Eu³⁺,0.03Sm³⁺ phosphor offers significant resistance to thermal quenching. The incorporation of lanthanide ion‐doped phosphors CSOE into PSCs is investigated along with their potential applications. The CSOE‐coated PSCs devices exhibit a high current density and a high power conversion efficiency (15.96%) when compared to the uncoated control devices.     

Plasmalichtquellen – Stand und Ausblick

Plasma Light Sources – Presence and Future Plasma light sources can at present fulfill all demands of general lighting with high efficiency. A further increase of the luminous efficacy and a high flexibility concerning the color temperature with simultaneous substitution of mercury as a filling substance – these are possible options. Solid‐state light sources will only start after some years to seriously compete with certain groups of plasma lamps     

Silicon-based oxynitride and nitride phosphors for white LEDs—A review

As a novel class of inorganic phosphors, oxynitride and nitride luminescent materials have received considerable attention because of their potential applications in solid-state lightings and displays. In this review we focus on recent developments in the preparation, crystal structure, luminescence and applications of silicon-based oxynitride and nitride phosphors for white light-emitting diodes (LEDs). The structures of silicon-based oxynitrides and nitrides (i.e., nitridosilicates, nitridoaluminosilicates, oxonitridosilicates, oxonitridoaluminosilicates, and sialons) are generally built up of networks of crosslinking SiN₄ tetrahedra. This is anticipated to significantly lower the excited state of the 5d electrons of doped rare-earth elements due to large crystal-field splitting and a strong nephelauxetic effect. This enables the silicon-based oxynitride and nitride phosphors to have a broad excitation band extending from the ultraviolet to visible-light range, and thus strongly absorb blue-to-green light. The structural versatility of oxynitride and nitride phosphors makes it possible to attain all the emission colors of blue, green, yellow, and red; thus, they are suitable for use in white LEDs. This novel class of phosphors has demonstrated its superior suitability for use in white LEDs and can be used in bichromatic or multichromatic LEDs with excellent properties of high luminous efficacy, high chromatic stability, a wide range of white light with adjustable correlated color temperatures (CCTs), and brilliant color-rendering properties.