Thin-film encapsulation for top-emitting organic light-emitting diode with inverted structure

We theoretically study the light outcoupling efficiency of top-emitting organic light-emitting diode(OLED) with inverted structure and thin-film encapsulation.Thin-film optics is used to optimize the layer thickness to obtain high transmittance.Dipole mode is used to analyze the light outcoupling efficiency of the top-emitting OLED.Through this process,we can optimize the thin-film thickness with high transmittance and optimize the outcoupling efficiency of OLED.Compared with previous research,the current design method is a novel process.     

Fabrication of high-rejection low-loss single-passband filters in cladding depressed fiber by the chirped-grating concatenation method

High-rejection-low-loss single-passband filters have been successfully fabricated by the chirped-grating concatenation method in a cladding depressed fiber. The enhanced photosensitivity, the enlarged bandgap between the Bragg resonance and the cladding modes, and the effective suppression of the cladding-mode outcoupling of the cladding depressed fiber permitted what is to our knowledge the first achievement of an ~1-dB loss in the passband and 50-dB rejection for a 50-nm-wide stop band covering the entire amplified spontaneous emission spectral range of an Er-doped fiber amplifier.     

一种改善红光顶发射OLED色纯度及角度依赖特性的方法研究

在Si/SiO₂衬底上生长金属银作为阳极,4,4,4-tris(3-methylphenylpheny-lamino)-triphenylamine(m-MTDATA):MoOx/m-MTDATA/N,N-bis-(1-naphthyl)-N,N-diphenyl-1,1-biphenyl-4,4-diamine(NPB)作为空穴注入及传输层,发光层采用4,4-N,N-dicarbazole-biphenyl(CBP)掺杂磷光染料(1-(phenyl)isoquinoline)iridium(III) acetylanetonate(Ir(piq)₂(acac))的结构,4,7-di-phenyl-1,10-phenanthroline(BPhen)作为空穴阻挡层及电子传输层,阴极为LiF(1 nm)/Al(2 nm)/Ag(20 nm)复合阴极结构.通过在光取出的复合阴极上方生长一层CBP光学覆盖层,有效地改善了复合阴极膜系的透射率,从而改善了顶发射结构的光学耦合输出特性,在提高器件的正向发光效率的同时还使色坐标往深红光区移动.并且生长光学覆盖层结构的器件角度依赖特性明显得到改善,这对于制作高显示质量的显示器件具有重要意义.在原有结构的基础上增加20 nm的NPB掺杂磷光染料Ir(piq)₂(acac)作发光层,从而得到双发光层结构为NPB:Ir(piq)₂(acac)(1%,20 nm)/CBP:Ir(piq)₂(acac)(1%, 20 nm).由于NPB具有较高的空穴迁移率,避免了由于光学厚度的增加而引起器件工作电压的大幅升高,而双发光层的结构有利于增大激子复合区域,提高辐射复合几率,减少非辐射损耗,实现主客体之间高效的三线态能量传递,相对单发光层顶发射结构,双发光层结构不仅提高了器件的发光效率,而且改善了器件的色坐标.     

基于ZnS增透膜的顶发射白光有机发光二极管

顶发射白光有机发光二极管(TEWOLED)在白光照明和全彩显示中有着良好的应用前景, 克服顶发射器件中的微腔效应是制备光电性能良好的TEWOLED的前提. 使用具有高折射率的ZnS作为增透膜改善金属阴极在蓝光波段的透射率,降低其反射性, 从而有效抑制了微腔的影响.同时利用转移矩阵理论和宽角干涉方法分别对阴极结构和 蓝光发光层位置进行了优化,最终获得了高效、色纯度良好、色度随视角变化小的TEWOLED. 最高亮度和效率分别达到9213 cd/m²和3 cd/A,色坐标位于白光区且接近白光等能点, 同时具有良好的视角稳定性,在0°---60°范围内色坐标仅变化(0.02, 0).     

Combined effects of microcavity and dielectric capping layer on bidirectional organic light-emitting diodes

We report on highly enhanced and controlled light outcoupling of bidirectional organic light-emitting diodes by introduction of an enhanced microcavity structure as well as an organic capping layer (OC). Combining both OC and microcavity, we find that the overall external quantum, as well as current efficiency (CE), can be greatly enhanced. Especially, the CE with an appropriate thickness of OC is almost 1.75 times larger than that of the reference device without OC. Furthermore, we also analyze our devices with a numerical optical model calculating the flux of outcoupled photons, and compare theoretical predictions with our experimental results.     

Increased and balanced light emission of transparent organic light-emitting diodes by enhanced microcavity effects

We report on improved and controlled light outcoupling of transparent organic light-emitting diodes (TOLEDs) by inserting thin silver layers between the indium tin oxide anode and the hole transporting layer. The introduction of Ag layers influences both the bottom and top emission of the TOLEDs, and it results in dramatic changes in the electroluminescence spectra and angular distribution. We find that the overall external quantum efficiency can be increased up to 18.8%, and the ratio of bottom and top emission can be almost identical.     

High-contrast organic light emitting diodes with a partially absorbing anode

To be legible in high-ambient light conditions, organic light-emitting-diode displays should be optically designed to have a minimal reflectance without significantly affecting their overall efficiency. We demonstrate the use of an anode consisting of a partially absorbing metal layer and a multilayer distributed Bragg reflector to simultaneously absorb rather than reflect incoming light and to take advantage of a weak microcavity effect in the diode to improve light outcoupling.     

Resonant coupling of surface plasmons to radiation modes by use of dielectric gratings

Efficient outcoupling of surface-plasma waves to radiation modes by use of dielectric diffraction gratings on a flat metallic surface is discussed. The dielectric gratings, which have a surface-relief structure with only several tens of nanometers in peak-to-trough height on a flat metal surface, can efficiently extract radiation modes propagating in free space from the surface-plasmon modes. An outcoupling efficiency of 50% is estimated with the rigorous coupled-wave diffraction theory, and it is confirmed by the experiment.     

Red top-emitting organic light-emitting device using 6, 13-di-(3, 5-diphenyl)phenylpentacene doped emitting system

Fluorescent red organic light-emitting devices (OLEDs) with narrow emission and negligible current-induced quenching by using a pentacene derivative of 6,13-di-(3,5-diphenyl)phenylpentacene (PDT) doped emitting system were demonstrated. With the incorporation of C₆₀ outcoupling layer, the PDT-based top-emitting OLED showed superior electroluminescence performances with Commission Internationale d’Eclairage color coordinates of (0.64, 0.36) and luminous efficiency of ～3 cd/A. To clarify the actual energy transfer process in PDT-doped emitting system, the Förster’s radius was calculated. The results indicated that the energy transfer process is predominantly from the host of tris(8-hydroquinoline) aluminum to guest of PDT via the assistant dopant of 5,6,11,12-tetraphenylnaphthacene.     

小半径弯曲条件下传能光纤传输效率研究

利用光线理论分析弯曲光纤模型中的包层光线传输特性,结合半导体激光模块传能尾纤弯曲实验表明,由于光纤弯曲有效数值孔径减小而进入包层的光线并未完全被耗散,当光纤弯曲部分长度较短时,部分未耗散掉的包层光在进入直光纤部分后仍可重新回到纤芯中进而长距离传输作为有用光输出。该结论表明弯曲光纤的传输效率由弯曲半径和弯曲光纤长度共同决定,即在光纤弯曲半径远小于传统理论临界半径的情况下,合理控制传能光纤弯曲部分的长度,仍可获得较高的传输效率。     

Al、Nd对Cr12MoV钢表面镍基熔覆层的组织及性能影响

为了解决Cr₁₂MoV钢溶蚀、表面碎裂等问题,利用Al-Ni、Nd-Ni粉末在Cr₁₂MoV钢上进行激光熔覆实验,研究了Al、Nd对镍基覆层的宏微观形貌、组织及表面性能的影响。结果表明:Al可以减少熔覆层裂纹的产生,同时降低覆层硬度,使熔覆层中产生具有减磨作用的硬质相Al₂O₃等,降低覆层磨损量,14%Al覆层磨损量比2%Al的覆层磨损量低44.5%,Al较优质量分数为14%;Nd的晶粒细化作用明显,显著提升覆层显微硬度,2.5%Nd覆层平均硬度比基体平均硬度高36.8%,Nd较优质量分数为2.5%。     

激光熔覆层开裂行为的影响因素及控制方法

激光熔覆层开裂是影响覆层质量最主要的因素,特别是厚覆层。选用５ｋＷ 横流ＣＯ２ 激光器对各种不同材料和零件进行厚覆层激光熔覆,实验、检测和使用的效果说明：激光熔覆层开裂主要与激光系统参数、工艺处理条件、覆层材料、基体状况等四个方面有关。分析了熔覆层的开裂行为,并介绍了几种控制方法。     

Bi‐directional organic light‐emitting diodes with nanoparticle‐enhanced light outcoupling

An effective method is presented for enhancing the outcoupling efficiency of translucent/bi‐directional organic light‐emitting diodes (TL/BD‐OLEDs) with a bottom indium tin oxide (ITO) anode and a top cathode comprised of a thin Ag layer covered with an organic capping layer. Upon insertion of a nanoparticle (NP)‐based scattering layer (NPSL) between the substrate and the ITO anode, the TL/BD‐OLEDs exhibit significantly enhanced external quantum efficiency (EQE) in both emission directions. Furthermore, the NPSL improves the color stability of the TL/BD‐OLEDs over a wide range of viewing angles. Simulations based on geometrical and statistical optics are performed to elucidate the mechanism by which the efficiency is enhanced and to establish strategies for further optimization. Simulations performed on the scattering layers with varying NP volume percentage reveal that the bottom‐side emission is governed by competition between waveguide‐mode extraction and backward scattering by NPs in the film, while the top‐side emission is largely dominated by the latter. Optimized bi‐directional OLEDs achieve a 1.64‐fold enhanced EQE compared to reference devices without NPSL.     

Grating coupler efficiency enhancement by double layer interference

A simple method for improving grating couplers' coupling efficiency without any extra microfabrication processes is proposed. This method can improve the coupling efficiency with 1.69 dB by utilizing the combined interference in the cladding layer and air gap between the cladding surface and the paralleled angle polished fiber facet. The proposed method can be applied to various kinds of on-chip grating couplers. Back reflection,1 dB bandwidth, and fiber alignment tolerance have also been improved at the same time.     

隧道再生四有源区大功率半导体激光器

利用隧道再生原理实现半导体激光器在低注入电流下的高光功率输出。通过传输矩阵法对隧道再生四有源区光耦合半导体激光器的模式特性进行了理论分析,指出器件的激射模式应为TE3,且存在最优的内限制层厚度。利用金属有机物化学气相沉积(MOCVD)外延法生长了内限制层厚度分别为0.3μm、0.5μm和0.7μm的器件。内限制层厚度等于0.5μm的器件的P-I特性最好,腔面未镀膜时,在2 A的注入电流下其光输出功率大于5 W,P/I斜率达2.74 W/A。结果表明,为了得到尽可能高的光输出功率,需要合理地设计隧道再生多有源区激光器的内限制层厚度。     

Monolithic integration of dual-layer optics into broad-area semiconductor laser diodes

A broad-area semiconductor laser diode with two monolithically integrated optical elements is presented. A 275-nm period detuned second-order diffraction grating on the p-doped side layer is combined with a refractive lens transferred into the GaAs substrate so that outcoupling and beam-shaping functions are decoupled. The high-power device produces a circular spot and demonstrates the potential of dual optics integration in broad-area semiconductor diodes.     

送粉角度对激光熔覆铁基复合涂层形状特征的影响

通过分析激光熔覆过程中光束、粉末和熔池间的作用机理,建立了送粉式激光熔覆材料有效利用率的数学模型,在此基础上推导了送粉角度与工艺参数之间的定量关系式,并计算了不同送粉角度下的熔覆材料有效利用率、熔高和横截面积。结果表明,在熔覆工艺参数不变的条件下,理论计算的熔覆材料有效利用率、熔覆层高度和横截面积均随送粉角度的增加而增大,且均高于实验检测值。激光熔覆过程中,由于粉末烧损和机械损失,使熔覆材料有效利用率、熔高和横截面积随送粉角度变化出现最大值,理想送粉角度为60。     

Light outcoupling efficiency enhancement in organic light emitting diodes using an organic scattering layer

Crystallized 4,7‐diphyenyl‐1,10‐phenanthroline (BPhen) films deposited by convenient vacuum thermal evaporation technique have been found to be an efficient means to extract the substrate wave guided light in organic light emitting diodes (OLEDs). The optimized BPhen film working as organic scattering layer was successfully used with OLEDs for light outcoupling efficiency improvement. Enhancement of 26%, 15% and 6% in efficiency of the blue, green and red OLEDs were obtained, respectively. The achievement was found to be advantageous in terms of simplicity of fabrication method and feasibility for large area OLED applications. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Plunging method for Nd : YAG laser cladding with wire feeding

The effects of wire feeding direction and position, cladding time, and cladding speed on the quality of cladding layer for laser cladding with wire feeding are studied. Experiment results indicate that the wire feeding direction and position are important for wire laser cladding. By adopting the correct wire feeding direction and position, the wire can be plunged into the melt pool and can be melted by the heat of the molten metal. With the increase of cladding speed, the dilution of clad layer can be reduced and the growth of the grain size of heat-affected zone of the base metal can be limited. If proper cladding parameters are used, the clad layers will have a good surface shape, sound metallurgical bonding with base metal, low dilution, and the effect of heating on heat-affected zone metal can be limited. The hardness of the clad layer and heat-affected zone are checked. It indicates that with the increase of cladding speed, the hardness of the clad layer and heat-affected zone increases.     

Cr对TiC-VC增强铁基熔覆层耐蚀性及耐磨性的影响

通过X射线衍射、扫描电子显微镜、能谱仪、极化曲线和磨粒磨损实验分析,研究了不同Cr加入量对TiC-VC增强铁基激光熔覆层耐蚀性和耐磨性能的影响。结果表明:熔覆层中物相主要为α-Fe,TiC,VC和TiVC2。随着Cr加入量的增加,伴随有残余奥氏体及Cr3C2的出现,且Cr3C2呈长条状部分聚集、部分单独分布。熔覆层的耐蚀性与耐磨性随Cr加入量的增加呈现先增加后降低的趋势。熔覆粉末中加入适量的Cr元素能显著提高熔覆层的硬度与耐蚀性。当添加质量分数为3.0%的Cr时,熔覆层硬度高达1090HV0.2,且相同磨损条件下熔覆层磨损失重仅约为Q235钢的1/26;当添加质量分数为9.0%的Cr时,所得熔覆层的耐蚀性最好,约为不添加Cr时的3.26倍。