White organic light-emitting devices utilizing a mixed color-conversion phosphor layer consisting of CaAl12O19:Mn and Zn2SiO4:Mn

White organic light-emitting devices (WOLEDs) were fabricated utilizing a mixed color-conversion layer consisting of CaAl12O19:Mn and Zn2SiO4:Mn phosphors. The ratio between the CaAl12O19:Mn and the Zn2SiO4:Mn phosphor determined the rate of the red and the green lights. The color rendering index was improved by using a mixed color-conversion phosphor layer.     

Single-composition trichromatic white-emitting Ca4Y6(SiO4)6O: Ce3+/Mn2+/Tb3+ phosphor: luminescence and energy transfer

A series of Ca(4)Y(6)(SiO(4))(6)O (CYS): Ce(3+)/Mn(2+)/Tb(3+) oxyapatite phosphors were prepared via high-temperature solid-state reaction. Under UV excitation, there exist dual energy transfers (ET), i.e., Ce(3+)→Mn(2+) and Ce(3+)→Tb(3+) in the CYS: Ce(3+), Mn(2+), Tb(3+) system and their emitting colors can be adjusted from blue to orange-red via ET of Ce(3+)→Mn(2+) and from blue to green via ET of Ce(3+)→Tb(3+), respectively. Moreover, a wide-range-tunable white light emission with high quantum yields (13%-30%) were obtained by precisely controlling the contents of Ce(3+), Mn(2+) and Tb(3+) ions. On the other hand, the CL properties of CYS: Ce(3+), Mn(2+), Tb(3+) phosphors have been investigated in detail. The studied results indicate that the as-prepared CYS: Ce(3+), Mn(2+), Tb(3+) phosphors have good CL intensity and CIE color coordinate stability with a color-tunable emission crossing the whole white light region under low-voltage electron beam excitation. In general, the white light with varied hues has been obtained in Ce(3+), Mn(2+), and Tb(3+)-triactivated CYS phosphors by utilizing the principle of energy transfer and properly designed activator contents under UV (284, 358 nm) and low-voltage (1-5 kV) electron beam excitation, which make them as a potential single-composition trichromatic white-emitting phosphor.     

Fabrication of nano-sized emitting phosphors for photoluminescence films via hydro-thermal synthesis

Nano-sized red and blue emitting phosphors for a photoluminescence film were fabricated via hydrothermal synthesis through the sol-gel process. The nano-sized phosphors had a spherical shape such as the 60-110 nm Y2O2S:Eu3+ phosphor and the 45-90 nm of Y2SiO5:Ce phosphor. Firing at 1000 degrees C for 2 hours resulted in an increase in their size to 90-190 nm for the Y2O2S:Eu3+ phosphor and 70-160 nm for the Y2SiO5:Ce phosphor. Heat treatment of the gel powders of the emitting phosphors above 730 degrees C was recommended because of their crystallization. The maximum excitation and emission intensities of the red and blue phosphors with Y2O2S:Eu3+ and Y2SiO5:Ce were at the wavelengths of 308 nm and 617 nm, and 254 nm and 464 nm, respectively. The photoluminescence of the films increased as increasing the content of the red and blue phosphor powder mixture in the plastic films. The 100 microm-thick PVB film with the nano-sized phosphors showed the maximum photoluminescence of 537 x 1000 counts/sec.     

LaMgAl11O19：Yb,Mn荧光粉中Yb^2＋与Mn^2＋的能量传递

利用共沉淀法制备了Yb和Mn离子共掺的LaMgAl11O19荧光粉。研究其室温下的发光性能。紫外光激发时观察到发光中心位于504nm的单一宽带发光峰,归因于Yb^2＋的激发态4f135d能级与基态4f14能级间的电子跃迁。同时观察到Yb和Mn共掺的LaMgAl11O19中存在Yb^2＋对Mn^2＋的传能现象,传能过程可...     

Luminescence properties of nano-crystalline Ba3MgSi2O8:Eu2+, Mn2+ phosphors

Ba3MgSi2O8:Eu2+, Mn2+ phosphors were synthesized by the sol-gel method and high temperature solid-state reaction method, respectively. XRD (X-ray diffraction), FT-IR (Fourier transform infrared spectroscopy), PL (photoluminescence spectra), and PLE (photoluminescence excitation spectra) were measured to characterize the samples. Emission and excitation spectra of our Ba3MgSi2O8:Eu2+, Mn2+ phosphors monitored at 441, 515, and 614 nm are depicted in the paper. The emission intensities of 441 and 515 nm emission bands increase with increasing Eu2+ concentration, while the peak intensity of the 614 nm band increases with increasing Mn2+ concentration. We conclude that the 515 nm emission band is attributed to the 4f(6)5d transition of Eu2+ ions substituted by Ba2+ sites in Ba2SiO4. The 441 nm emission band originates from Eu2+ ions, while the 614 nm emission band originates from Mn2+ ions of Ba3MgSi2O8:Eu2+, Mn2+. Nano-crystalline Ba3MgSi2O8:Eu2+, Mn2+ phosphors prepared by the sol-gel method show higher color rendering and better color temperature in comparison with the samples prepared by high temperature solid-state reaction method.     

Synthesis of green emitting and transparent zn2siO4:mn2+ thin film phosphors on 2D photonic crystal patterned quartz substrates

Zn2SiO4:Mn2+ thin film phosphors (TFPs) have been synthesized by RF magnetron sputtering, using a single multicomponent stoichiometric target. And 2D photonic crystal patterns were introduced on a quartz substrate to enhance the light extraction efficiency. In order to introduce 2D photonic crystal patterns on a quartz substrate, nanosphere lithography was used. Polystyrene spheres, with diameter of 330 nm, were transferred on the quartz substrate and subsequently were served as an etch mask. Quartz substrates were patterned by CF4 gas-based reactive ion etching. Zn2SiO4:Mn2+ were deposited on that 2D photonic crystal patterned quartz substrate and the effect of height of photonic crystal layers were investigated. The light extraction efficiency of Zn2SiO4:Mn2+ thin film phosphors deposited on the photonic crystal patterned quartz substrate was enhanced three times to compared with that of flat Zn2SiO4:Mn2+ thin film phosphors due to the Bragg diffraction and leaky mode caused by PCLs. Transmittance of Zn2SiO4:Mn2+ TFPs deposited on the photonic crystal patterned substrate was high enough, above 70% in the visible light region with respect to that of quartz substrate.     

Synthesis and luminescence properties of Sr2SiO4: Eu3+, Dy3+ phosphors by the sol-gel method

The Sr2SiO4:Eu3+, Dy3+ phosphors for white light emitting diodes (LEDs) were synthesized by the sol-gel method. The microstructure and luminescent properties of the obtained Sr2SiO4:Eu3+, Dy3+ particles were well characterized. The results demonstrate that the Sr2SiO4:Eu3+, Dy3+ particles, which have spherical morphology, emitted an intensive white light emission under excitation at 386 nm. The phosphors show three emission peaks: the blue emission at 486 nm corresponding to the 4F(9/2)-6H(15/2) transition of Dy3+, the yellow emission at 575 nm corresponding to the 4F(9/2)-6H(13/2) transition of Dy3+, and the red emission at 615 nm corresponding to the 5D0-7F2 transition of Eu3+. At the same time, the effect of Eu3+ concentration on the emission intensities of Sr2SiO4:Eu3+, Dy3+ was investigated in detail. The phosphors used for white LEDs were obtained by combining near ultraviolet (NUV) light (386 nm) with Sr2SiO4:0.04Dy3+, 0.01Eu3+ phosphors with the characteristic of Commission Internationale de l'Eclairage (CIE) chromaticity coordinate (x, y) of (0.33, 0.34), and color temperature Tc of 5,603 K. In addition, the effect of the charge compensators (Li+, Na+, and K+ ions) on the photoluminescence (PL) emission intensities were studied.     

溶胶-凝胶法制备CaAl_2SiO_6:Eu~(2+)荧光粉及其光学性质的研究

采用溶胶-凝胶法制备了CaAl2SiO6∶Eu2+荧光粉,利用X射线衍射仪、荧光光谱仪、热分析仪对其结构和光学性质进行了研究.结果表明,样品经1 000℃CaAl2SiO6∶Eu2+荧光粉在430 nm附近的发光峰为Eu2+中心的4f65d1(t2g)→4f7(8S7/2)跃迁;随Eu2+离子浓度的增加,样品的发光强度先增加后降低,在Eu2+浓度为0.7 mol%时达到最大;CaAl2SiO6∶Eu2+系列荧光粉的激发峰波长在280~390 nm之内,可以作为一种新型的UV-LED用三基色荧光粉.     

Study on luminescence behavior of BaAl12O19:Tb, Eu

BaAl12O19:Tb, Eu phosphors were prepared by sol-gel technique. The luminescence properties and the energy transfer between Eu2+ and Tb3+ were investigated. For BaAll2O19:Tb phosphor, the strongest excitation peak and emission peak produced from Tb3+ transition of 5D4-7F5 were at 240 nm and at 550 nm respectively, while the peak shape was narrow and peak intensity was large. The Eu2+ added in the BaAl12O19:Tb induced energy transfer to Tb3+ and different color luminescence from blue (400 nm) to green (570 nm) was obtained by changing the ratio of Tb3+/Eu2+ with excitation at 240 nm.     

新型白光LED用SrMg_2(PO_4)_2单-基质荧光粉

本文通过高温固相法合成了紫外光LED用SrMg2(PO4)2为基质Eu2+,Tb3+和Mn2+为激活剂的白色荧光粉。采用XRD对荧光粉的结构和相纯度进行分析,Eu2+、Tb3+及Mn2+的加入对其结构没有明显的影响,且无杂相生成;当用Ca部分取代Sr时Eu2+和Mn2+的发射带分别发生红移和蓝移且二者之间存在着明显的能量传递;当引入共激活剂Tb3+时对其荧光光谱进行了详细研究,发现Eu2+和Tb3+,Eu2+和Mn2+之间存在部分的能量传递,通过调整它们的相对掺杂浓度可以得到发白光的荧光粉。     

Luminescence mechanisms of organic/inorganic hybrid organic light-emitting devices fabricated utilizing a Zn2SiO4:Mn color-conversion layer

Zn₂SiO₄:Mn phosphor layers used in this study were synthesized by using the sol-gel method and printed on the glass substrates by using a vehicle solution and a heating process. Organic/inorganic hybrid organic light-emitting devices (OLEDs) utilizing a Zn₂SiO₄:Mn color-conversion layer were fabricated. X-ray diffraction data for the synthesized Zn₂SiO₄:Mn phosphor films showed that the Zn ions in the phosphor were substituted into Mn ions. The electroluminescence (EL) spectrum of the deep blue OLEDs showed that a dominant peak at 461 nm appeared. The photoluminescence spectrum for the Zn₂SiO₄:Mn phosphor layer by using a 470 nm excitation source showed that a dominant peak at 527 nm appeared, which originated from the ⁴T₁-⁶A₁ transitions of Mn ions. The appearance of the peak around 527 nm of the EL spectra for the OLEDs fabricated utilizing a Zn₂SiO₄:Mn phosphor layer demonstrated that the emitted blue color from the deep blue OLEDs was converted into a green color due to the existence of the color-conversion layer. The luminescence mechanisms of organic/inorganic hybrid OLEDs fabricated utilizing a Zn₂SiO₄:Mn color-conversion layer are described on the basis of the EL and PL spectra.     

Fabrication of SiO2@ZrO2@Y2O3:Eu3+ core-multi-shell structured phosphor

ZrO2 interface was designed to block the reaction between SiO2 and Y2O3 in SiO2@Y2O3:Eu coreshell structure phosphor. SiO2@ZrO2@Y2O3:Eu core-multi-shell phosphors were successfully synthesized by combing an LBL method with a Sol-gel process. Based on electron microscopy, X-ray diffraction, and spectroscopy experiments, compelling evidence for the formation of the Y2O3:Eu outer shell on ZrO2 were presented. The presence of ZrO2 layer on SiO2 core can block the reaction of SiO2 core and Y2O3 shell effectively. By this kind of structure, the reaction temperature of the SiO2 core and Y2O3 shell in the SiO2@Y2O3:Eu core-shell structure phosphor can be increased about 200-300 degrees C and the luminescent intensity of this structure phosphor can be improved obviously. Under the excitation of ultraviolet (254 nm), the Eu3+ ion mainly shows its characteristic red (611 nm, 5D0-7F2) emissions in the core-multi-shell particles from Y2O3:Eu3+ shells. The emission intensity of Eu3+ ions can be tuned by the annealing temperatures, the number of coating times, and the thickness of ZrO2 interface, respectively.     

Eu2+、Dy3+、Li+共掺杂CaSi2O2N2荧光粉的发光性能

采用高温固相反应法制备了一系列白光LED用CaSi2O2N2:0.05Eu2+,xDy3+,xLi+(0≤x≤0.03)荧光粉.利用X射线衍射仪对样品的物相结构进行了分析,结果表明:Dy3+和Li+离子的掺入没有改变CaSi2O2N2:Eu2+荧光粉的主晶相.利用荧光光谱仪对样品的发光性能进行了测试,发现所有样品的激发光谱均覆盖了从近紫外到蓝光的较宽范围,400 nm激发下得到的发射光谱为宽波段的单峰,峰值位于545 nm左右,是Eu2+离子5d-4f电子跃迁引起的.Dy3+离子掺杂可以提高CaSi2O2N2:Eu2+荧光粉的发光强度,Dy3+与Li+共掺杂可进一步提高荧光粉的发光强度,当Dy3+和Li+的掺杂量为1mol%时,荧光粉的发光强度达到最大值,是单掺杂Eu2+的荧光粉发光强度的157%.     

GeO2 dopant induced enhancement of red emission in CaAl12O19:Mn phosphor

In order to search efficient red-emitting phosphors for white LEDs application, CaAl₁₂O₁₉:Mn⁴⁺ phosphors have been prepared by a combustion method assisted with GeO₂ flux. The influence of GeO₂ concentration and annealing temperature on the structure and luminescence intensity for the phosphors has been investigated. The mechanism for luminescence enhancement has been discussed. At GeO₂ doping concentration of 1.5 mol%, the red emission intensity increases by 81% under 330 nm UVA excitation. More isolated luminescence center Mn⁴⁺ ions rather than pairs of Mn⁴⁺-Mn²⁺ ions are formed in the lattice with the introduction of GeO₂ at high temperature oxidation, leading to the enhancement of the red emission. A feasible new way to enhance the red emission in CaAl₁₂O₁₉:Mn⁴⁺ phosphor is obtained.     

有机半导体照明(有机照明)研究进展

采用有机发光二极管(OLEDs)的有机半导体照明(有机照明)是绿色环保、健康安全的新型面光源,有望在固态照明领域得到广泛的应用。有机照明的发展是随着有机发光材料的不断进步而进步的。有机发光材料从最初的荧光材料发展到磷光材料以及最近提出的热活化延迟荧光材料,其性能在不断地提升。基于这些材料的白光OLEDs的性能也在不断提升。最早的白光器件基于荧光小分子材料,但是由于只能利用单线态激子发光,效率很低。随后磷光材料的引入使得白光器件的效率大幅度提升,但是由于蓝色磷光材料本身的稳定性问题,全磷光白光器件的寿命较短。为了结合荧光和磷光的优点,人们提出了荧光/磷光杂化的白光器件,这是目前最有前景的一类白光器件结构。目前针对有机照明的研究,已从早期只关注效率突破阶段,进入到综合提高效率和寿命阶段。从荧光白光、磷光白光以及荧光/磷光混合白光3个方面对有机照明的研究状况、发展趋势进行了介绍。     

A study of ZnGa2O4 phosphor prepared by the solid method

In this study, the mixtures of ZnO and Ga2O3 powder with addition of LiCl flux were fired, the raw material mixing ratio, doping with Mn2+ and firing atmosphere effects on phosphor characteristics were investigated. When fired at 1200 °C, its phosphor powder emits a broad-band spectrum range between 375 nm to 700 nm, with a peak at 470 nm. The optimal composition of phosphors is about ZnO/Ga2O5=47/53. Manganese-doped ZnGa2O4, fired in air, exhibits two new emission bands with peaks at 506 nm (Mn2+ emission centre) and 666 nm (Mn4+ emission centre). However, if fired under vacuum, the emission spectrum presents only the 506 nm peak with increased intensity. The 666 nm emission peak derived from a little Mn2 oxidized to Mn4+ which substituted Ga3+ to occupy the B sites of the spinel structure. The emission intensity of the 506 nm peak of Zn1-xMnxGa2O4 is strongest when [Mn2+] x=0.006 and decreases markedly as the concentration of Mn2+ exceeds x=0.01. Most of the substitutional Mn2+ doping species in spinel ZnGa2O4 occupy the zinc sites. The luminescent band was associated to the spin-forbidden transition, 4T1(4G)6A1 (6S). © 1998 Kluwer Academic Publishers     

White luminescence of Dy3+ ions doped 12CaO 7Al2O3 nanopowders under UV light excitation

12CaO 7Al2O3:Dy3+ nanopowders were successfully synthesized by the chemical co-precipitation method. X-ray diffraction result shows that the single 12CaO 7Al2O3 phase is formed with Dy3+ ions to replace the Ca2+ ions in the host of 12CaO 7Al2O3. The yellow and blue emissions, attributed to the forced electric dipole transition of 4F(9/2) --> 6H(13/2) centered at 571 nm and the magnetic dipole transition of 4F(9/2) --> 6H(15/2) centered at 480 nm, respectively, were observed. The integrated intensity ratios of yellow to blue increase from 1.63 to 1.70 with Dy3+ concentration increasing from 0.8 to 2.0% for the as-prepared 12CaO 7Al2O3:xDy3+ phosphor. The significantly enhanced emission intensities of 12CaO 7Al2O3:1.0% Dy3+ phosphor annealed at 900 degrees C for 2 hours in vacuum ambient could be ascribed to the decrease of OH(-) groups and the change of the surface topography. The thermal stability and the Commission International de l'Eclairage coordinates were also investigated. All the photoluminescence characteristics indicate that Dy3+ ions doped 12CaO 7Al2O3 may be a good candidate for the solid state lighting phosphor as well as white light-emitting diodes.     

Temperature-Dependent Luminescence Characteristic of SrSi2O2N2：Eu2＋ Phosphor and Its Thermal Quenching Behavior

The yellow SrSi2O2N2：Eu2＋ phosphor has been synthesized by using a simple solid-state reaction method with Sr2SiO4：Eu2＋ as the precursor. It shows a broad excitation band extending from 250 to 520 nm and an asymmetric emission band with a main peak at about 550 nm. The emission intensity of the SrSi202N2：Eu2＋ is about 1.2 times higher than the commercial yellow phosphor YAG：Ce3＋ （P46-Y3）. The temperature- dependent luminescence characteristic of SrSi202N2：Eu2＋ has been investigated in this paper. With increasing temperature, the emission band of SrSi202N2：Eu2＋ shows anomalous blue-shift along with decreasing emission intensity and the broadening full width at half maximum （FWHM）. Particularly, compared with YAG：Ce3＋ （P46-Y3）, the yellow SrSi202N2：Eu2＋ phosphors exhibit higher thermal stability due to their weaker electron-phonon coupling strength （1.1）, lower stokes shift （0.0576 eV） and larger activation energy （0.288 eV）. All these results indicate that SrSi202N2：Eu2＋ yellow phosphors have potential application for white light-emitting diodes （LEDs）, What＇s more, an energy level scheme is constructed to explain the anomalous blue-shift phenomenon.     

Synthesis of micrometer SrAl2Si2O8 :Eu, Dy blue phosphor powders via sol- gel process

In this paper, we report on long- persistence white phosphor SrAl2Si2O8 :Eu2 , Dy3 synthe-sized by the sol - gel method. The luminescent materials prepared by the sol - gel method have many ad-vantages, such as uniform composition, high purity, fine grains and low synthesis temperature. We foundthat SrAl2Si2O8 :Eu2 ,Dy3 phosphor prepared by the sol -gel method can provide more luminescent in-tensity and better afterglow characteristic compared with the same phosphor prepared by solid -statemethod. Namely, the particle size and shape of phosphors should be optimized to obtain the maximumquantum efficiency through energy absorption. The mierostrueture of the phosphor consisted of regularfine grains with an average size of about 0.5. - 1 μm. Under 356 nm light excitation, the broadband emis-sion of the phosphor continues from 350 to 650 ntn and the emission peak is at about 414 nm, which canbe viewed as the typical emission of Eu2 ascribed to the 4f→5d transitions.     

白光LED用BaMgAl_(10)O_(17):Eu~(2+)Mn~(2+)蓝绿荧光粉

采用高温固相法制备出一种Eu2+,Mn2+共掺的蓝绿色荧光粉BaMgAl10O17:Eu2+,Mn2+(BAM:Eu2+,Mn2+),对其进行了X射线衍射分析和光谱特性的测试.研究表明,它的发射光谱为双峰结构,峰值分别位于455 nm和525 nm处.455 nm发射峰归结为BAM中部分取代Ba2+离子的Eu2+离子的5d→4f的跃迁辐射;525 nm的发射峰源于部分Eu2+能量传递给Mn2+离子,Mn2+的4T1→6A1的跃迁辐射.采用近紫外LED芯片与该荧光粉以及一种红色荧光粉Ca(La0.5Eu0.5)4Si3O13封装,在20 mA前向电流驱动下,获得了显色指数为88的白光LED.