Die spektrale Verteilung der Thermolumineszenz von elektrolumineszenten ZnSCu-Phosphoren

The thermoluminescence of electroluminescent ZnSCu-phosphors was measured after electrical excitation and its spectral distribution was determined for the temperature of the glow peaks. Though the electroluminescence of the investigated powders showed a blue and a green emission band there was only a green emission to be observed in the thermoluminescence above 130°K. This effect can be explained using the theory of hole migration.     

CdS单晶中的绿色电致发光和光致发光

在50-290K温度范围内,研究了在正向电压激发下,用高纯CdS单晶制备的MIS发光二极管的电致发光光谱。在室温时,发射光谱分别由峰值为5135±25Å和5300±15Å的二个绿色谱带所组成,而在低温下,观测到有很多结构的光谱。在50K时,自由和束缚激子的发射实际上占有统治地位。文中提出,在室温时,谱峰为5135±25Å的谱带是与受导带自由电子散射的自由激子的发射有关;而谱峰为5300±15Å的谱带归结为与同时发射二个纵光学声子的自由激子的发射有关。比较了刚生长的高阻CdS单晶以及在熔融镉中热处理的低阻CdS单晶的光致发光光谱。在熔融镉中的热处理抑制了自由到束缚(HES)和束缚到束缚(LES)的边缘发射,也抑制了I2束缚激子谱线,但是增强了自由激子的发射,在电场激发下,也使自由激子的发射增强。     

Depth-resolved cathodoluminescence study of zinc oxide nanorods catalytically grown on p-type 4H-SiC

Optical properties of ZnO nanorods (NRs) grown by vapour-liquid-solid (VLS) technique on 4H-p-SiC substrates were probed by cathodoluminescence (CL) measurements at room temperature and at 5 K complemented with electroluminescence. At room temperature the CL spectra for defect related emission intensity was enhanced with the electron beam penetration depth. We observed a variation in defect related green emission along the nanorod axis. This indicates a relatively poor structural quality near the interface between ZnO NRs and p-SiC substrate. We associate the green emission with oxygen vacancies. Analysis of the low-temperature (5 K) emission spectra in the UV region suggests that the synthesized nanorods contain shallow donors and acceptors.     

Emission tuning study of RGB blends. Interaction of two EL polymers and a red dye

A study of light emission in photo- and electroluminescence in blends composed of a blue and a green emitting polymers with a red dye was performed. To gain information about the tunability of the RGB mixture, the blends varied in composition. The polymers were poly(2,7-9,9′-dihexylfluorenediyl) (blue), poly(9,9-di-hexylfluorenediyl divinylene-alt-1,4-phenylenevinylene) (green) and the dye was 4-(dicyanomethylene)-2-methyl-6-(dimethylaminostyryl)-4H-pyrane (red).It was verified that in photoluminescence Forster type energy transfer plays the main role in the emission. In solution a large concentration of the acceptors is needed to attain the transfer radii, whereas in the solid state, the transfer is very sensitive to small variations in the acceptor content, with large changes in emission spectra. The band gaps of the components allowed a cascade energy transfer mechanism. In electroluminescence, apart from the energy transfer mechanism, an important role is played by the trapping of charge carriers, resulting in significant differences between the PL and EL spectra.     

Improvement of green InGaN-based LEDs efficiency using a novel quantum well structure

The green light emitting diodes(LEDs)have lower quantum efficiency than LEDs with other emission wavelengths in the visible spectrum.In this research,a novel quantum well structure was designed to improve the electroluminescence(EL)of green InGaN-based LEDs.Compared with the conventional quantum well structure,the novel structure LED gained 2.14times light out power(LOP)at 20-mA current injection,narrower FWHM and lower blue-shift at different current injection conditions.     

Effect of chlorine concentration on the spectral characteristics of electroluminescence in ZnS: Cu: Cl phosphor

ZnS: Cu: Cl phosphor prepared under a vacuum firing process is found to give blue electroluminescence with emission peak at 460 nm which remains unaltered with the frequency of the excitation voltage. Addition of excess chlorine in the phosphor gives blue, green and red emission at 460, 520 and 640 nm. The intensity of the blue band decreases and it finally disappears as chlorine concentration is increased. A scheme involving three energy levels attributed to Cu²⁺, Cu⁺ and Cl^- centres in ZnS explains the experimental results completely.     

有机薄膜电致发光器件在反向偏压下的电致发光

合成了性能优良的聚合物--聚对苯乙烯,并采用甩胶方法制备了单层薄膜电致发光器件ITO/PPV/Al.在所制备的器件上观察到反向偏压下的电致发光现象,记录了在不同反向偏压下的电致发光光谱,测量了在反向偏压下的电流和发光强度,初步讨论了有机发光器件在反向偏压下的发光机理.     

有机薄膜的光致发光和电致发光

制备了以Alq3为发光物质的有机薄膜电致发光器件,得到了30V直流电压下100cd/m2的绿色发光.探讨了Alq3薄膜的光致发光和器件的电致发光机理.     

Synthesis and electroluminescent property of dinuclear aluminum 8-hydroxyquinoline complex

A new structural dinuclear aluminum 8-hydroxyquinoline complex (DAlq₃) with two aluminum chelate-center was designed and synthesized. It was assessed as light-emitting material in organic light-emitting device (OLED). The green light emission was observed in films and OLEDs. DAlq₃ has better electron mobility and also shows a higher electroluminescence (EL) efficiency than that of aluminum 8-hydroxyquinoline (Alq₃).     

可变色的钕和铒注入的ZnS发光二极管

利用离子注入技术制备ZnS发光二极管,当激发参数改变时,电致发光给出不同的发射颜色。一种类型ZnS发光二极管是将Nd离子注入到ZnS的一个表面,而Er离子注入到另一个表面,两而的电极做成条状并彼此交错,仪当反向偏压时才给出电致发光,因而外加电压改变极性时,二极管将是绿色(Er3+)或橙色(Nd3+)发光。第二种类型ZnS发光二极管是将Er和Nd离子注入到ZnS的同一表面,但是不同的深度,当外加电压的大小改变时,二极管发光颜色可以从绿色到橙色或者从橙色到绿色。     

基于CdSe纳米晶发光器件的电致发光特性的研究

以巯基乙酸为稳定剂,在水溶液中制备了硒化镉(CdSe)纳米晶。用X射线光电子能谱(XPS)及其在水溶液中的紫外可见吸收光谱对其进行了表征。又以CdSe为发光材料制备了两种结构的电致发光器件,并对它们的光致发光和电致发光特性进行了研究。在两个器件的电致发光中都得到了CdSe纳米晶的发光,说明CdSe纳米晶是主要的发光中心而聚乙烯咔唑(PVK)只是空穴注入和传输的媒介。在电致发光光谱中还出现了一个不同于CdSe纳米晶和PVK的发光峰值,它是CdSe/BCP(2,9-二甲基-4,7-二苯基-1,10-菲咯啉)界面处的电致发光激基复合物的发光。     

Electroluminescence from ZnO nanowires with a p-ZnO film/n-ZnO nanowire homojunction

ZnO homojunction light-emitting diodes based on ZnO nanowires were fabricated on Si(100) substrates. An N–In codoped p-type ZnO film grown by ultrasonic spray pyrolysis and an unintentionally doped n-type ZnO nanowire quasi-array grown by an easy low-temperature hydrothermal method were employed to form the homojunction diode. Under a forward bias larger than 8 V, electroluminescence, which was composed of an ultraviolet peak centered at 387 nm and a green band around 540 nm, was observed. The electroluminescence emission was contributed by the ZnO nanowires. The results reported here suggest that ZnO-based ultraviolet light-emitting devices could be realized at low cost. PACS 42.72.Bj; 73.40.Lq; 85.60.Jb     

铽配合物Tb(o-MBA)3phen与PVK掺杂体系的发光机理

合成了一种新型的稀土铽配合物材料Tb(o-MBA)₃phen,并把它作为发光材料应用于有机电致发光器件中。将铽配合物与PVK的混合溶液用旋涂法制得发光层,并利用Alq₃作为电子传输层制备了多种结构的电致发光器件:器件A:ITO/PVK:Tb(o-MBA)₃phen/LiF/Al;器件B:ITO/PVK:Tb(o-MBA)₃phen/BCP/Alq₃/LiF/Al;器件C:ITO/BCP/PVK:Tb(o-MBA)₃phen/Alq₃/LiF/Al。由器件A和C得到了纯正的、明亮的Tb³⁺的绿光发射,发射光谱中四个特征峰分别对应着能级⁵D₄→⁷F_J(J=6,5,4,3)的跃迁,而PVK的发光完全被抑制。在光致发光中PVK的发射光谱和铽配合物的激发光谱有一定的重叠,两者之间可能存在Frster能量传递。同时PVK与铽配合物掺杂体系的激发光谱与纯PVK的激发光谱非常相像,而与铽配合物的激发光谱差别很大,这也说明掺杂体系中铽的发光有一部分来源于PVK分子的激发,PVK与铽配合物之间存能量传递过程。研究了掺杂体系的电致发光性能,在电致发光中,铽的发光主要来源于稀土配合物直接俘获载流子形成激子并复合发光。通过优化选择得到了发光性能较好的器件,器件的最大亮度在17V时达到180cd/m²。     

C-ZnSe:Ga的室温蓝色注入式发光

本文首次报导了C-ZnSe:Ga的室温蓝色注入式发光,测量了有关特性并讨论了发光机理.电致发光光谱具有强的4800A的蓝峰和弱的6300A的红峰.随着正向电压的增加,6300A的自激活发射相对减弱,而4800A的蓝色边缘发射逐渐增强.因此,当电压增加时,发光颜色由红色经黄色和绿色,逐渐变成纯蓝色.在明亮的房间里可以观察到鲜明的蓝色发射.文末提出了ZrSe多色显示的设想.     

Photoluminescence and electroluminescence by gallium(III) complexes of N-salicylidene-o-aminophenol and its derivatives

N-salicylidene-o-aminophenol and two of its derivatives bearing either an electron-donating methyl group or an electron-withdrawing Br group were used as ligands for the synthesis of three Ga(III) complexes. The complexes involved the participation of one acetylacetonate and one ethanol or methanol molecule. The geometry of the dianion of the Schiff base in the complexes is planar while photoluminescence data showed that photoluminescence intensity was extensively increased upon complex formation. Complexes emitted ligand-centered luminescence by ligand-centered excitation. Substituent groups broadly modified emission maximum. These substitutions can be exploited to tune light emission by the complex. All three complexes were used for the construction of electroluminescence devices and all emitted electroluminescence. Both photoluminescence and electroluminescence emission was enhanced in the case of substituted Schiff bases.     

铽配合物Tb(BA)3phen的有机电致发光

合成了一类新型稀土配合物Tb(BA)3phen,将其掺杂到导电聚合物PVK中获得了纯正、明亮的绿光发射.用这种搀杂体系分别制作了单层发光器件和双层器件.对于单层器件,掺杂浓度为15,甩膜转速1000 r·min-1时器件的发光效果最好,起亮电压为10V,最大亮度在21 V时可达26.8cd·m-2.双层器件用AlQ作为电子传输层,通过改变其厚度得到了发光性能较好的用AlQ作为电子传输材料的器件,其最大亮度在22 V时可达322cd·m-2.     

有机磷光材料的固态阴极射线发光研究

采用有机磷光材料三-(2-苯基吡啶)-铱(Ir(PPY)₃)与无机材料SiO₂复合制成夹层结构器件,用交流电压驱动获得了Ir(PPY)₃主峰位于517nm的发光和主峰位于435nm的蓝色发光.通过分析器件的光谱特性,发现这两个发光峰都是源于SiO₂中加速电子直接碰撞激发有机层引起的固态阴极射线发光.继实现多种有机聚合物材料和有机小分子材料八羟基喹啉铝(Alq₃)的固体阴极射线发光之后,又证实了有机 关键词： 夹层结构器件 有机磷光材料 固态阴极射线发光     

GaP纯绿发光二极管的近红外发光研究

本文测量了GaP纯绿发光二极管在室温和液氮温度下的近红外发光光谱,观测到许多重叠的宽带发光.按高斯线型对光谱进行拟合,将其分解为6个发光谱峰,讨论了这些深能级发光的来源和它们对GaP发光二极管的发光强度的影响.     

两种铽配合物与PVK混合体系的发光机理研究

研究了稀土配合物Tb(p-MBA)₃phen(样品Ⅰ)和Tb(p-ClBA)₃phen(样品Ⅱ)与导电聚合物材料PVK掺杂体系的光致发光和电致发光特性。发现在样品Ⅰ与PVK混合薄膜的光致发光中,除了三价铽离子的发光外,还能看到明显的PVK的发光;而在电致发光中,PVK的发光完全被抑制,只能看到Tb3+的绿光发射。对样品Ⅱ与PVK的混合发光层,无论其光致发光谱还是电致发光谱,都没有看到410 nm处PVK的发射。进一步测量两种材料的激发光谱,初步探讨了器件的发光机理。样品Ⅰ的发光可能来源于两个方面,一是PVK到稀土配合物的不完全的能量传递,二是由于载流子俘获机理;样品Ⅱ的发光则是由于PVK到稀土配合物的完全的能量传递。     

Electroluminescence of colloidal ZnSe quantum dots

The article reports a green chemical synthesis of colloidal ZnSe quantum dots at a moderate temperature. The prepared colloid sample is characterised by UV-vis absorption spectroscopy and transmission electron microscopy. UV-vis spectroscopy reveals as-expected blue-shift with strong absorption edge at 400 nm and micrographs show a non-uniform size distribution of ZnSe quantum dots in the range 1-4 nm. Further, photoluminescence and electroluminescence spectroscopies are carried out to study optical emission. Each of the spectroscopies reveals two emission peaks, indicating band-to-band transition and defect related transition. From the luminescence studies, it can be inferred that the recombination of electrons and holes resulting from interband transition causes violet emission and the recombination of a photon generated hole with a charged state of Zn-vacancy gives blue emission. Meanwhile electroluminescence study suggests the application of ZnSe quantum dots as an efficient light emitting device with the advantage of colour tuning (violet-blue-violet).