磷光与荧光相结合的多层白色有机发光器件

采用真空热蒸镀的方法制备了磷光与荧光相结合的 多层白色有机电致发光器件(OLED)。将绿 光磷光掺杂染料掺杂到母体CBP中作为绿光发光层;荧光材料 DCM2以亚单层的方式插入Alq₃中作为红光发光层;DPVBi为蓝光发光层。器件的结构为ITO /NPB(40nm)/DPVBi(d nm)/CBP:Ir(ppy)₃₈%(5nm)/ Alq₃(5nm)/DCM2(0.05nm)/Alq₃(45nm)/LiF(1nm)/AI(200nm)。实验中通过改变蓝光发 光层的厚度,得到了高效率的 白光OLED,器件的最大电流效率可达6.75cd/A,最大功率效率达2.67lm/W,最大亮度 达30440cd/m²。此外,当电压从4V变化到14V时色坐标从(0.59,0.39)变化到(0.35,0.38), 基本处于白光区。本文器件的特点在于其性能可以通过简单调整DPVBi的厚度,避免 了使用多掺杂层工艺的复杂性。     

间隔层提高有机电致发光器件的性能

使用不同的有机材料作为间隔层,制备了基于CB P材料的一系列红绿双发光层有机 电致发光器件(OLED),其结构为ITO/MoO₃(50nm)/NPB(40nm)/TCTA(10 nm)/CBP:R-4B(20nm,2%)/ 间隔层(3nm)/CBP:GIr1(30nm,14%)/BCP(10 nm)/Alq₃(20nm)/LiF(1nm)/Al(100nm),其中间隔 层材料使用BCP、TPBi和TCTA。实验比较了加入不同间隔层后OLED的发光特性,结果显 示,对发光面积为0.8cm²的器件,当器件加入间隔层后,电流效 率和亮度有很大提高,用 TCTA作间隔层时得到器件的最大效率为39.98cd/A,最大亮度为29790cd/m²;并且使用间隔 层后OLED发光性能稳定,电致发光(EL)光谱和色坐标不随驱动电压的变化而产生变化。     

含镁多元合金阴极绿色磷光有机电致发光器件

为进一步提高有机电致发光器件(OLED)电子载流 子的注入水平,简化制备工艺,采用Ca:Mg:Al三元合金作为OLED阴极,制备了结构为ITO/Mo O₃/NPB/TCTA/CBP:GIr1/TPBi/Alq₃/Mg(x%):Ca:Al的绿色磷 光OLED,分析了Mg在提高器件电子注入水平、平衡载流子浓度中的作 用及其原理。实验通过优化合金阴极中Mg的含量,得到了亮度为41830cd/m²、电流效率稳定在26cd/m²左右的高效稳定的绿色磷光O LED。     

蓝绿色磷光OLED的制备及发光性能研究

以mCP为主体发光材料,蓝绿色磷光染料BGIr1作 为掺杂剂,制备了6种不同BGIr1掺杂量的蓝绿色磷光有机电致发光器件(OLED),研究了不 同掺杂量对蓝绿色磷光OLED器件发光特性的影 响。制得器件的结构为ITO/MoO₃(20nm)/NPB(40nm)/mCP:BGIr1(x%,30nm)/BCP(10nm)/Alq₃(20 nm)/LiF/Al(100nm),其中x%为发光层中磷光染料BGIr1的掺杂量(质量分数)。结果表明,BGIr1掺杂量 为18%时,获得器件的发光性能最佳。18% BGIr 1掺杂器件在488nm和 512nm处获得两个主发射峰,当电 流密度为26.5mA/cm²时,获得最大发光效率为6.2cd/A;在15V驱动电压下,获得最大亮度为6970cd/cm², CIE坐标为(0.17,0.31)。这说明,BGI r1掺杂改善了器件的发光亮度和色纯度,提高了器件的发光效率。     

白光有机电致发光器件发光稳定性研究

基于红绿/蓝双发光层,制作了结构为ITO/MoO ₃(10nm)/NPB(40nm)/TCTA(10nm)/CBP:R-4B(2%):GIR1(14%,X nm)/mCP:Firpic(8%,Y nm/BCP(10nm)/Alq₃(40nm)/LiF(1nm)/Al( 100nm)的白色全磷光有机电致发光器件(OLED),通过 调节红绿发光层的厚度X与蓝光发光层的厚度Y,研究了不同发光层厚度器件发 光性能的影响。研究发现:当X 为23nm、Y为7nm时,器件的光效和色坐标都具有 很高的稳定性,在电压分别为5、 10和15V时,色坐标分别为(0.33,0.37)、(0.33,0. 37)和(0.34,0.38);在电压为 5V时,电流密度为0.674mA,亮度为158.7cd ,最大电流效率为26.87cd/A;利用电子阻 挡材料TCTA和空穴阻挡材料BCP能够显著提高载流子的复合效率。分析认为:发光层顺序 为红绿/蓝时,更有利于蓝光的出射,从而使白光的色坐标更稳定。     

发光性能稳定的磷光与荧光复合型白光OLED

使用荧光染料TBPe和Ir(ppy)_2acac 、R-4B两种光染料,采用蓝/红绿双发光层的结构,并结合TPBi对空穴的有效限制作用 ,制备了结构为ITO/MoO₃(X nm)/ADN:(2%)TBPe(30 nm)/CBP:Ir(ppy)_2acac(14%):R-4B(2%)(5nm)/TPBi(10 nm)/Alq₃(30nm)/LiF(1nm )/Al(100nm)的磷光与荧光复合的白光OLED,其中,MoO₃的厚 分别为0、15、20、30和40nm,通过改变MoO₃的厚度调控载流子的注入能力,使用空穴阻挡层提高光效; 通过测量其电压、电流、亮度、色坐标和电致发光(EL)光谱等参数,研究不同厚度的MoO ₃对器件发光性能的影响。结果表明,在MoO₃厚为20nm的情况下,器件的效率滚降 最为平缓。在电压分别 为8、9、10、11、12和13V时,器件的色坐标分别为 (0.31,0.33)、(0.30,0.33)、(0.29,0.33)、(0.29,0.33)、(0.29,0.33)和(0.29, 0.33),具有较高的稳定性,原因为采用 蓝/红绿双发光层结构更有利于蓝光的 出射,且使用ADN主体材料掺杂蓝色荧光染料TBPe作为蓝光发光层降低三重态-三重态 湮灭几率。 研究还发现,在电压为11V、器件的亮度为9744cd/m²和电流密度为11.50mA/cm²时,最大器件的电流效率为 7.0cd/A。     

以DCJTB为颜色转换层的三原色WOLED研究

对一系列蓝光和蓝绿光器件展开研究,发现结构为ITO/NPB(40nm)/mCP(5nm)/mCP∶FIrpic(30nm)/TPBi(2nm)/TPBi∶Ir(ppy)₃(10nm)/TmPyPB(40nm)/LiF(1nm)/Al的蓝绿光器件具有最佳光电性能,其电流效率高达38.3cd/A。基于该结构,结合采用红色荧光染料DCJTB制备的颜色转换层实现了三原色白色有机发光二极管(White Organic Light-emitting Diode,WOLED)。结果表明,器件性能可通过DCJTB浓度进行调控,当其浓度为0.7%时,实现了电流效率为23.9cd/A、色坐标为(0.35,0.43)及色温为5121K的WOLED,且电流密度从1mA/cm²变化到100mA/cm²,其色坐标仅漂移(0.005,0.003)。     

基于CdSe/ZnS和Alq3的白光量子点LED的研究

采用CdSe/ZnS红光量子点(QD),利用旋涂和真 空蒸镀工艺制备了结构为ITO/TPD+PVK/QDs/Alq₃/LiF/Al的量 子点发光器件(QD-LED),并对器件的发光性能做了测试。研究了ITO表面处理、TPD空穴 传输层和QD发光层的厚 度对QD-LED性能的影响,并通过调整QD发光层和Alq₃电子传输层的 厚度,制备了可用于照明 的白光QD-LED。实验结果表明,ITO的表面处理可有效降低器件的开启电压,开启 电压从9V降到7V左右; TPD空穴传输层和QD发光层的厚度对器件的电流密度和发光亮度有较大的影响,而Alq₃电 子传输层和QD发光层 的合理配比可以混合出较高色温的白光。通过优化器件各参数,当TPD和PVK质量比为5∶1、QD度为1.0mg/ml和 Alq₃厚为60nm时,制备的器件在15V电压 时发光效率达到了1500c d/m²,色坐标为(0.3628,0.3796) ,显色指数为88.1。     

基于DOPPP的高效白光OLED器件

采用真空热蒸镀的方法,以荧光染料1-(2,5-d imethoxy-4-(1-pyrenyl)-phenyl)pyrene (DOPPP)为蓝发光 层,5,6,11,2-Tetraphenylnaphthacene (Rubrene)为黄发光层,制备了结构为ITO/m-M TDATA(10nm)/NPB(30nm)/ Rubrene (0.2nm)/ DOPPP (x nm)/TAZ(10nm)/Alq₃(30nm)/LiF(0.5nm)/Al的双发光层的高效白色有机电 致发光器件(OLED)。通过调整DOPPP层的厚度,研究器件的发光性能。当DOPPP层厚小 于25nm时,器件以 黄光发射为主;当DOPPP层厚为25nm时器件的性能最佳,在电流密度为209.18mA/cm²时,获得最 大亮度为9232cd/m²,在电流密度为103.712mA/cm²时获得最大电流效率4.68cd/A, 并随着驱动电压 的升高,器件的色坐标从(0.366,0.365)变化到(0.384,0.399),都在白光的范围之内;当DOPPP层厚度超过25nm时,器件的效率和亮度 都开始下降。     

蓝光磷光微腔有机电致发光器件特性的研究

使用典型蓝色磷光材料Firpic作为磷光金属微腔 有机电致发光器件(OLED)的发光层, 以高反射的Al膜作为阴极顶电极和半透明的Al膜作为阳极底电极,其结构为 Glass/Al(15nm)/MoO₃(30nm)/NPB(40nm)/mCP:Firpic(30nm,x%)/BCP(10nm)/Alq(20nm)/LiF (1nm)/Al(100nm),x%为Firpic的掺杂 质量分数,分别为4%、6%、10%、12%和14%。实验 制备了不同的OLED,比较了测量角度和不同掺杂浓度对OLED发光特性的影响。结 果显示,对发光面积为0.8cm²的器件,测量角度的不同导致蓝光 辐射波长蓝移,色坐标发 生变化,器件的510nm和472nm两个峰值变化 不相同,随着角度的增大, 较大的峰值不断衰减,而较小的峰值不断增强;并且,当掺杂浓度为12%时,OLED得 到最好的发光性能,12V电压驱动下有最大亮度18870cd/m²,说明此时的主客体间能量转移最充分。     

Improved property in organic light-emitting diode utilizing two Al/Alq3 layers

We reported on the fabrication of organic light-emitting devices (OLEDs) utilizing the two Al/Alq₃ layers and two electrodes. This novel green device with structure of Al(110 nm)/tris(8-hydroxyquinoline) aluminum (Alq₃)(65 nm)/Al(110 nm)/Alq₃(50 nm)/N,N′-dipheny1-N, N′-bis-(3-methy1phyeny1)-1, 1′-bipheny1-4, 4′-diamine (TPD)(60 nm)/ITO(60 nm)/Glass. TPD were used as holes transporting layer (HTL), and Alq₃ was used as electron transporting layer (ETL), at the same time, Alq₃ was also used as emitting layer (EL), Al and ITO were used as cathode and anode, respectively. The results showed that the device containing the two Al/Alq₃ layers and two electrodes had a higher brightness and electroluminescent efficiency than the device without this layer. At current density of 14 mA/cm², the brightness of the device with the two Al/Alq₃ layers reach 3693 cd/m², which is higher than the 2537 cd/m² of the Al/Alq₃/TPD:Alq₃/ITO/Glass device and the 1504.0 cd/m² of the Al/Alq₃/TPD/ITO/Glass. Turn-on voltage of the device with two Al/Alq₃ layers was 7 V, which is lower than the others.     

Multifunctional Fluorene‐Based Oligomers with Novel Spiro‐Annulated Triarylamine: Efficient,Stable Deep‐Blue Electroluminescence,Good Hole Injection,and Transporting Materials with Very High Tg

A series of fluorene‐based oligomers with novel spiro‐annulated triarylamine structures, namely DFSTPA, TFSTPA, and TFSDTC, are synthesized by a Suzuki cross‐coupling reaction. The spiro‐configuration molecular structures lead to very high glass transition temperatures (197–253 °C) and weak intermolecular interactions, and consequently the structures retain good morphological stability and high fluorescence quantum efficiencies(0.69–0.98). This molecular design simultaneously solves the spectral stability problems and hole‐injection and transport issues for fluorene‐based blue‐light‐emitting materials. Simple double‐layer electroluminescence (EL) devices with a configuration of ITO/TFSTPA (device A) or TFSDTC (device B)/ TPBI/LiF/Al, where TFSTPA and TFSDTC serve as hole‐transporting blue‐light‐emitting materials, show a deep‐blue emission with a peak around 432 nm, and CIE coordinates of (0.17, 0.12) for TFSTPA and (0.16, 0.07) for TFSDTC, respectively, which are very close to the National Television System Committee (NTSC) standard for blue (0.15, 0.07). The maximum current efficiency/external quantum efficiencies are 1.63 cd A^?1/1.6% for device A and 1.91 cd A^?1/2.7% for device B, respectively. In addition, a device with the structure ITO/DFSTPA/Alq₃/LiF/Al, where DFSTPA acts as both the hole‐injection and ‐transporting material, is shown to achieve a good performance, with a maximum luminance of 14 047 cd m^?2, and a maximum current efficiency of 5.56 cd A^?1. These values are significantly higher than those of devices based on commonly usedN,N′‐di(1‐naphthyl)‐N,N′‐diphenyl‐[1,1′‐biphenyl]‐4,4′‐diamine (NPB) as the hole‐transporting layer (11 738 cd m^?2 and 3.97 cd A^?1) under identical device conditions.     

利用石墨烯掺杂在NPB中的OLED性能研究

采用NPB掺杂石墨烯作为空穴传输层,制备有机电致发光器件(OLED),器件结构为ITO/NPB:Graphene(20wt.%)(50nm)/Alq3(80nm)/LiF(0.5nm)/Al(120nm)。将其与标准器件ITO/NPB(50nm)/Alq3(80nm)/LiF(0.5nm)/Al(120nm)作性能比较,研究石墨烯对OLED性能的影响。结果表明,在NPB中掺杂石墨烯薄层的器件,在同等条件下性能最佳,当电流密度为90mA/cm2时器件电流效率达到最大值3.40cd/A,与标准器件最高效率相比增大1.49倍;亮度在15V时达到最大值10 070cd/m2,比标准器件最大亮度增大5.16倍。     

功能层界面制备方法对OLED性能的影响

在功能层界面处采用各功能材料共蒸的方法,制备了典型的绿光有机发光器件(OLED)。器件的结构为ITO/NPB(37nm)/(NPB:Alq3)(3nm)/Alq3(27nm):C545T(3%)/Alq3(20nm)/LiF(1nm)/Al(100nm),并与传统的制备方法进行了比较。结果发现,起亮电压从4.5V降低到2.5V,最高耐压从16V提高到21V,最大亮度从13 940cd/m2提高到24 630cd/m2,发光效率由7.0cd/A提高到11.4cd/A。结果表明,本文方法有利于载流子传输,可以有效提高激子形成概率,提高了OLED发光效率。     

High performance blue organic light-emitting devices fabricated by using the doped AIq3 in NPB hole transmistion layers

We have designed a new structure blue emission device with doped Alq3 of 3% in hole transmission layers of NPB. The CIE coordination of the devices is （0.17,0.19）. The maximum electroluminescence efficiency is 4.1 cd/A at 11 V, the brightness is 118.8 cd/m^2 at 7 V, and the maximum brightness is 10770 cd/m^2 at 13 V.     

Blue top-emitting organic light-emitting devices using Alq3 as phase shift adjustment layer

Blue top-emitting organic light-emitting devices (TEOLEDs) are demonstrated by employing Alq3 as phase shift adjustment layer (PSAL) to increase the phase shift on reflection of the top electrode within a range, which also improves the light out-coupling. By adjusting the thickness of PSAL, the CIEx,y of devices, which utilize 2, 7-Di-pyrenyl-9, 9-spiro-bifluorene (DPSF) as emitting layer, changes from (0.16, 0.50) to (0.18, 0.37). The maximum current efficiency of 7.1 cd/A is acquired under 4.5 V with an increasing luminance of 139 cd/m2. Compared with adjusting the total thickness of organic layer, it is more beneficial for achieving blue TEOLEDs with high efficiency.     

High‐Tg Carbazole Derivatives as Blue‐Emitting Hole‐Transporting Materials for Electroluminescent Devices

A series of dicarbazolyl derivatives bridged by various aromatic spacers and decorated with peripheral diarylamines were synthesized using Ullmann and Pd‐catalyzed C–N coupling procedures. These derivatives emit blue light in solution. In general, they possess high glass‐transition temperatures (T_g > 125 °C) which vary with the bridging segment and methyl substitution on the peripheral amine. Double‐layer organic light‐emitting devices were successfully fabricated using these molecules as hole‐transporting and emitting materials. Devices of the configuration ITO/HTL/TPBI/Mg:Ag (ITO: indium tin oxide; HTL: hole‐transporting layer; TPBI: 1,3,5‐tris(N‐phenylbenzimidazol‐2‐yl)benzene) display blue emission from the HTL layer. The EL spectra of these devices appear slightly distorted due to the exciplex formation at the interfaces. However, for the devices of the configuration ITO/HTL/Alq₃/Mg:Ag (Alq₃ = tris(8‐hydroxyquinoline)aluminum) a bright green light from the Alq₃ layer was observed. This clearly demonstrates the facile hole‐transporting property of the materials described here.