LPPP异质结构薄膜发光器性能增强的研究

研究了以空穴型梯型聚次苯基（LPPP）和电子型八羟基喹啉铝（Alq3）组成的光发射器发射效率提高的方法，发光器的结构为Au／LPPP／Alq3／Al，测试结果表明这种发光器微腔调谐效应显著，净发射效率得到提高。     

有机小分子掺杂的聚合物共混发光二极管

报道了用可溶性发光材料聚（２,５－二丁氧基苯）做发光材料,分别与母体聚合物聚乙烯基咔唑（ＰＶＫ）和聚甲基丙烯酸甲脂（ＰＭＭＡ）共混,并掺杂电子传输材料叔丁基联苯基苯基口恶二唑和空穴传输材料二胺衍生物作发光层,用铟锡氧化物和铝分别作正负电极,制作了两种蓝紫光有机／聚合物单层发光器件。通过比较两种器件的器件特性,发现以ＰＭＭＡ做母体的器件比用ＰＶＫ做母体的器件有更好的稳定性,器件开启电压为１０Ｖ左右,发光峰值波长均位于４２４ｎｍ,电致发光效率可达２．９％,比用ＰＶＫ做母体的器件效率高一倍多。     

Highly Emissive and Color‐Tunable CuInS2‐Based Colloidal Semiconductor Nanocrystals: Off‐Stoichiometry Effects and Improved Electroluminescence Performance

The off‐stoichiometry effects and gram‐scale production of luminescent CuInS₂‐based semiconductor nanocrystals, as well as their application in electroluminescence devices are reported. The crystal structures and optical properties of CuInS₂ nanocrystals can be significantly influenced by controlling their [Cu]/[In] molar ratio. A simple model adapted from the bulk materials is proposed to explain their off‐stoichiometry effects. Highly emissive and color‐tunable CuInS₂‐based NCs are prepared by a combination of [Cu]/[In] molar ratio optimization, ZnS shell coating, and CuInS₂–ZnS alloying. The method is simple, hassle‐free, and easily scalable to fabricate tens of grams of nanocrystal powders with photoluminescence quantum yields up to around 65%. Furthermore, the performance of high‐quality CuInS₂‐based NCs in electroluminescence devices is examined. These devices have lower turn‐on voltages of around 5 V, brighter luminance up to approximately 2100 cd m^?2 and improved injection efficiency of around 0.3 lm W^?1 (at 100 cd m^?2) in comparison to recent reports.     

无机、有机LED和EL白色发光及绿色照明

用无机白色ＬＥＤ照明由于不含Ｈｇ，因而无公害，被称为绿色照明。描述了无机ＬＥＤ的特性及进展，特别描述了与发光粉结合成新的白光ＬＥＤ的发展动态；同时还评述了无机白光ＥＬ和有机ＥＬ白光发射在绿色照明应用的可能性。     

Si基发光的研究进展

回顾了Si基发光的研究历程,归纳分析了新近几种实现Si发光的方法和其优缺点,其中包括多孔Si发光、GeSi/Si量子阱发光、Sip-n结位错发光、CMOSSi基发光、PERL结构Si基发光等方法。重点介绍了PERL结构Si基发光,分析了结构设计中的几个关键性因素。该结构利用了光电转换可逆性原理,基于普通的单光子和双光子辅助次禁带弱光发射过程,通过把位于有关的次禁带波长的吸收最小化,同时减少二极管内寄生无辐射复合的作用范围。期望通过该综述提高国内研究者对PERLSi基发光的重视,开拓以PERL为新思路、新方法的Si基光互连方向研究的新进展。     

被动驱动有机发光二极管矩阵屏老化性能的研究

对102×64点阵的单色被动驱动的有机电致发光(OLED)矩阵屏进行了老化研究。矩阵屏的结构为ITO/CuPc/NPB/Alq3∶C545/LiF/Al。测量了老化前后矩阵屏的电流-电压-亮度曲线,以及电致发光(EL)和光致发光光谱(PL)。比较发现,老化后的器件在同样恒电流的情况下表现出更高的驱动电压,更小的漏电流,以及在阴极和有机层界面上电致发光和光致发光的光谱强度减弱。矩阵屏在老化17 h后,电致发光和光致发光的强度分别降低到初始值的75.6%和81.4%,分析认为,这是因为老化过程中部分发光材料分解,从而造成对矩阵屏的永久损伤。     

阻挡层结构的蓝色有机发光二极管

制备了ITO／CuPc/NPB/TPBi/Alq3/MgAg有机发光二极 管,由于阻挡层TPBi对空穴的阻挡作用,器件的电致发光为NPB特征光谱,实现了蓝色发光。器件最大亮度和最大流明效率分别为3700cd/cm^2和0.78 lm/W,CIE色坐标为x=0.110 ,y=0.085,色度纯正。然而器件显现出较差的稳定。利用器件的能级结构,分析了器件的光学特性和影响稳定性的因素。     

微腔有机发光二极管

设计了由分布布拉格反射镜（ＤＢＲ）和金属反射镜面形成的微腔结构。利用８－羟基喹啉铝（Ａ１ｑ３）作为电子传输层兼作发光层,ＴＰＤ作为空穴传导层,了有机发光二极管（ＯＬＥＤ）和微腔有机发光二极管（ＭＯＬＥＤ）。发现ＭＯＬＥＤ的光谱工比ＯＬＥＤ的窄得多,而光密度则得到了增强,对腔长进行调节,ＭＯＬＥＤ光谱峰出现移动。实验结果与理论计算基本符合。     

Triplet Harvesting in Hybrid White Organic Light‐Emitting Diodes

White organic light‐emitting diodes (OLEDs) are highly efficient large‐area light sources that may play an important role in solving the global energy crisis, while also opening novel design possibilities in general lighting applications. Usually, highly efficient white OLEDs are designed by combining three phosphorescent emitters for the colors blue, green, and red. However, this procedure is not ideal as it is difficult to find sufficiently stable blue phosphorescent emitters. Here, a novel approach to meet the demanding power efficiency and device stability requirements is discussed: a triplet harvesting concept for hybrid white OLED, which combines a blue fluorophor with red and green phosphors and is capable of reaching an internal quantum efficiency of 100% if a suitable blue emitter with high‐lying triplet transition is used is introduced. Additionally, this concept paves the way towards an extremely simple white OLED design, using only a single emitter layer.     

Meeting High Stability and Efficiency in Hybrid Light‐Emitting Diodes Based on SiO2/ZrO2 Coated CsPbBr3 Perovskite Nanocrystals

Significant advances are realized in perovskite‐converted hybrid light‐emitting diodes (pc‐HLEDs). However, long‐living devices at high efficiencies still represent a major milestone with average stabilities of < 200 h at ≈ 50 lm W^?1 under low applied currents ( < 15 mA). Herein, a dual metal oxide‐coated CsPbBr₃@SiO₂/ZrO₂ composite is prepared in a one‐pot synthesis through the kinetic control of the sol–gel reaction, followed by a gentle drying process in air. These hybrid nanoparticles show photoluminescence quantum yields of ≈ 65% that are stable under temperature, ambient, and irradiation stress scenarios. This is translated to pc‐HLEDs with a near‐unity conversion efficiency at any applied current, high efficiencies around 75 lm W^?1, and one of the most remarkable stabilities of ≈ 200 and 700 h at 100 and 10 mA, respectively. In addition, the device degradation mechanism is thoughtfully rationalized comparing devices operating under ambient/inert conditions. As such, this work provides three milestones: i) a new room temperature one‐pot protocol to realize the first SiO₂/ZrO₂ metal oxide coating that effectively protects the emitting perovskite nanoparticle core, ii) one of the most stable and efficient pc‐HLEDs operating under ambient condition at any applied current, and iii) new insights for the degradation of pc‐HLEDs.     

基于磷光材料的有机电致白光器件的研究进展

有机电致白光器件是近年来国际上的一个研究热点,它不仅可以作为液晶显示的背光源,也是未来照明技术的有效光源。有机磷光电致发光可以同时利用单重态和三重态的激子,理论上可使器件的内量子效率达到100%,而在近几年倍受关注。文章介绍了磷光材料的有机电致白光器件的研究进展,按多发射层、多重掺杂单发射层、单重掺杂单发射层以及基于激发二聚体和激基复合物发射4种结构进行了分析和阐述。     

Fluorene‐Based Asymmetric Bipolar Universal Hosts for White Organic Light Emitting Devices

Two new bipolar host molecules composed of hole‐transporting carbazole and electron‐transporting cyano ( CzFCN ) or oxadiazole ( CzFOxa )‐substituted fluorenes are synthesized and characterized. The non‐conjugated connections, via an sp³‐hybridized carbon, effectively block the electronic interactions between electron‐donating and ‐accepting moieties, giving CzFCN and CzFOxa bipolar charge transport features with balanced mobilities (10^?5 to 10^?6 cm² V^?1 s^?1). The meta–meta configuration of the fluorene‐based acceptors allows the bipolar hosts to retain relatively high triplet energies [E_T = 2.70 eV ( CzFOxa ) and 2. 86 eV ( CzFCN )], which are sufficiently high for hosting blue phosphor. Using a common device structure – ITO/PEDOT:PSS/DTAF/TCTA/host:10% dopants (from blue to red)/DPPS/LiF/Al – highly efficient electrophosphorescent devices are successfully achieved. CzFCN ‐based devices demonstrate better performance characteristics, with maximum η_ext of 15.1%, 17.9%, 17.4%, 18%, and 20% for blue (FIrpic), green [(PPy)₂Ir(acac)], yellowish‐green [m‐(Tpm)₂Ir(acac)], yellow [(Bt)₂Ir(acac)], and red [Os(bpftz)₂(PPhMe₂)₂, OS1], respectively. In addition, combining yellowish‐green m‐(Tpm)₂Ir(acac) with a blue emitter (FIrpic) and a red emitter (OS1) within a single emitting layer hosted by bipolar CzFCN , three‐color electrophosphorescent WOLEDs with high efficiencies (17.3%, 33.4 cd A^?1, 30 lm W ^?1), high color stability, and high color‐rendering index (CRI) of 89.7 can also be realized.     

新型低压高效叠层有机白光器件

以Bphen:Li/WO3作为电荷产生层制备了低压、高效有机叠层白光器件. 实验中,首先在器件中引入高导电性的载流子注入和传输层,有效降低了器件的驱动电压,然后通过电荷产生层垂直堆叠两个低压白光器件,获得了低压、高效有机叠层白光器件. 叠层器件性能与单发光单元的器件相比较,其亮度及效率均有大幅提高,叠层器件的最大电流效率达到了17cd/A,在相同的电流密度下,叠层器件的效率约为传统器件的2.3倍,同时由于在叠层结构中引入了高导电性的载流子传输层,有效降低了器件的驱动电压,显著改善了白光器件的流明效率.叠层器件的流明效率相对于单发光单元器件提高了53%.     

基于ITO键合技术的白光发光二极管特性研究

根据色度学原理计算,通过选择匹配的基色波长和功率,制备了GaN/GaAs基ITO键合白光发光二极管(LED),得到了等能白光。通过测试发现,在20mA下,电压为5.3V,此方法是制备固态照明用白光LED的有效方法之一。     

新型低压高效叠层有机白光器件

以Bphen:Li/WO3作为电荷产生层制备了低压、高效有机叠层白光器件.实验中,首先在器件中引入高导电性的载流子注入和传输层,有效降低了器件的驱动电压,然后通过电荷产生层垂直堆叠两个低压白光器件,获得了低压、高效有机叠层白光器件.叠层器件性能与单发光单元的器件相比较.其亮度及效率均有大幅提高,叠层器件的最大电流效率达到了17cd/A,在相同的电流密度下,叠层器件的效率约为传统器件的2.3倍.同时由于在叠层结构中引入了高导电性的载流子传输层,有效降低了器件的驱动电压,显著改善了白光器件的流明效率.叠层器件的流明效率相对于单发光单元器件提高了53%.     

以Liq∶Rubrene为发光层的白色有机电致发光器件的研制

以蓝色发光材料Liq为主体,以一定的比例掺入黄光染料Rubrene,研制了新型白色有机电致发光器件.调节Rubrene的掺杂比为1.1%时得到近白光器件,色坐标为(0.308,0.347),器件的启亮电压为8V,当外加电压达到25V时,器件发光亮度达3120cd/m2.     

Centimeter‐Sized Cs4PbBr6 Crystals with Embedded CsPbBr3 Nanocrystals Showing Superior Photoluminescence: Nonstoichiometry Induced Transformation and Light‐Emitting Applications

An HBr‐assisted slow cooling method is developed for the growth of centimeter‐sized Cs₄PbBr₆ crystals. The obtained crystals show strong green photoluminescence with absolute photoluminescence quantum yields up to 97%. More importantly, the evolution process and structural characterizations support that the nonstoichiometry of initial Cs₄PbBr₆ crystals induce the formation of nanosized CsPbBr₃ nanocrystals in crystalline Cs₄PbBr₆ matrices. Furthermore, high efficiency and wide color gamut prototype white light‐emitting diode devices are also demonstrated by combining the highly luminescent Cs₄PbBr₆ crystals as green emitters and commercial K₂SiF₆:Mn⁴⁺ phosphor as red emitters with blue emitting GaN chips. The optimized devices generate high‐quality white light with luminous efficiency of ≈151 lm W⁻¹ and color gamut of 90.6% Rec. 2020 at 20 mA, which is much better than that based on conventional perovskite nanocrystals. The combination of improved efficiency and better stability with comparable color quality provides an alternative choice for liquid crystal display backlights.     

白色发光二极管色坐标和显色指数的一致性

白色发光二极管已经成为发光二极管家族中的一员 ,由于其在“绿色照明工程”中的巨大发展潜力 ,因而受到人们的广泛重视。白色发光二极管在制备过程中与其他颜色发光二极管不同的是它需要加上涂粉工艺 ,涂粉的一致性对白色发光二极管的色坐标和显色指数的影响非常大 ,而色坐标和显色指数是照明光源的重要技术指标。美国光谱技术公司制备的白色发光二极管的色坐标范围为Ｘ =0 .2 8～ 0 .3 8,Ｙ =0 .2 8～ 0 .3 8。在我们制备的白色发光二极管中任意选取 1 0只 ,对其色坐标和显色指数进行了测试 ,色坐标的平均值为Ｘ =0 .3 1 ,Ｙ =0 .3 3 ,色…     

脊形波导大功率发光二极管

采用自对准工艺制作的分段吸收式脊形波导结构发光二极管，在出光面蒸镀λ／４介质增透膜，以增大器件的自发辐射发量，增大器件耦合效率。光束发散角小。用标准单摸光纤耦事，在２５℃、１００ｍＡ下的光功率大于２０μＷ，最大可达５０μＷ。用７０支器件在５０、８０、１２０℃及１５０ｍＡ ＣＷ条件下进行加速老化寿命试验，在测试３５５０ｈ后，共计２４８５００器件小时，没有一支器件失效，器件性能稳定可靠。用测试结果可计     

High‐Performance Hybrid White Organic Light‐Emitting Diodes with Superior Efficiency/Color Rendering Index/Color Stability and Low Efficiency Roll‐Off Based on a Blue Thermally Activated Delayed Fluorescent Emitter

Thermally activated delayed fluorescence (TADF)‐based white organic light‐emitting diodes (WOLEDs) are highly attractive because the TADF emitters provide a promising alternative route to harvest triplet excitons. One of the major challenges is to achieve superior efficiency/color rendering index/color stability and low efficiency roll‐off simultaneously. In this paper, high‐performance hybrid WOLEDs are demonstrated by employing an efficient blue TADF emitter combined with red and green phosphorescent emitters. The resulting WOLED shows the maximum external quantum efficiency, current efficiency, and power efficiency of 23.0%, 51.0 cd A^?1, and 51.7 lm W^?1, respectively. Moreover, the device exhibits extremely stable electroluminescence spectra with a high color rendering index of 89 and Commission Internationale de L'Eclairage coordinates of (0.438, 0.438) at the practical brightness of 1000 cd m^?2. The achievement of these excellent performances is systematically investigated by versatile experimental and theoretical evidences, from which it is concluded that the utilization of a blue‐green‐red cascade energy transfer structure and the precise manipulation of charges and excitons are the key points. It can be anticipated that this work might be a starting point for further research towards high‐performance hybrid WOLEDs.