激基复合物和磷光超薄层相结合的高效率非掺杂白光有机发光二极管

将蓝光激基复合物mCP∶PO-T2T和磷光超薄层结合,分别制备了基于Ir（pq）₂acac（～0.5 nm）/mCP∶PO-T2T/Ir（pq）₂acac（～0.5 nm）结构的双色互补色和基于Ir（ppy）₃（～0.5 nm）/mCP∶PO-T2T/Ir（pq）₂acac （～0.5 nm）结构的三基色非掺杂白光有机发光二极管（White organic light emitting diodes, WOLED）,以探索超薄层在激基复合物中的应用。所制备的双色互补色WOLED,其最大电流效率、功率效率和外量子效率分别为46.1 cd/A、43.9 lm/W和22.2%,而三基色WOLED所实现的最大电流效率、功率效率和外量子效率分别为66.8 cd/A、63.5 lm/W和24.2%。研究分析表明,从高能的蓝光激基复合物发光层向两侧低能的红光和绿光磷光超薄层有效的能量传递是实现非掺杂WOLED高效率的原因。     

基于超薄发光层及双极性混合间隔层的白光有机发光器件研究

本文采用非掺杂超薄发光层及双极性混合间隔层结构,获得了高效、光谱稳定的白光有机发光器件.基于单载流子器件及单色蓝光有机发光器件的研究,确定了双极性混合间隔层的最佳比例;通过瞬态光致发光寿命研究,验证了不同发光材料之间的能量传递过程;得到的三波段和四波段白光有机发光器件的最高效率分别为52 cd/A (53.5 lm/W)和13.8 cd/A (13.6 lm/W),最高外量子效率分别为17.1%和11.2%.由于发光层不同颜色之间依次的能量传递结构,三波段白光有机发光器件的亮度从465到15950 cd/m~2时,色度坐标的变化?CIE仅为(0.005, 0.001);四波段白光有机发光器件的亮度从5077到14390 cd/m~2时,色度坐标的变化?CIE为(0.023, 0.012).     

绿色磷光微腔有机电致发光器件研究

使用典型绿色磷光材料Ir(ppy)3作为发光层,DBR和金属Al作为微腔的一对反射镜,制备了结构为Glass/DBR/ITO/Mo O3(1 nm)/Tc Ta(40 nm)/CBP:Ir(ppy)3(40 nm,6%)/TPBI(47 nm)/Li F(1 nm)/Al(80 nm)的绿色磷光微腔有机电致发光器件(MOLED),同时制作了无腔对比OLED器件,研究微腔结构对器件发光性能的影响。发现OLED的电致发光谱(EL)的峰值是510 nm,半峰全宽(FWHM)为70 nm,MOLED的峰值是514 nm,FWHM为35 nm,比OLED窄化了1/2,MOLED的最大亮度、最大电流效率分别为143000 cd/m2和64.4 cd/A,OLED的最大亮度、最大电流效率分别为103000 cd/m2和41.6 cd/A;测试并计算了器件的外量子效率(EQE),MOLED和OLED的最大EQE分别为18.6%和14.3%。结果表明,微腔器件发光性能比无腔器件得到了很大的改善。     

红色磷光微腔有机电致发光器件的发光性能

制备了结构为G/DBR/ITO/Mo O3(1 nm)/Tc Ta(55 nm)/CBP∶Ir(piq)2acac(44 nm,6%)/TPBI(55nm)/Li F(1 nm)/Al(80 nm)的红色磷光微腔有机电致发光器件(MOLED),同时制作了无腔对比器件OLED,研究微腔结构对磷光器件发光性能的影响。研究发现,OLED的电致发光(EL)峰值为626 nm,半高全宽(FWHM)为92 nm;MOLED的发光峰值为628 nm,FWHM为42 nm,窄化了1/2。MOLED的最大亮度、最大电流效率、最大外量子效率(EQE)分别为121 000 cd/m2、27.8 cd/A和28.4%,OLED的最大亮度、最大电流效率、最大EQE分别为54 500 cd/m2、13.1 cd/A和16.6%。结果表明,微腔器件的发光性能与无腔器件相比得到了较大幅度的提升。     

基于溶液加工小分子材料发光层的有机-无机复合发光器件

报道了基于溶液加工有机小分子材料发光层、聚乙烯亚胺电子注入层的有机-无机复合发光器件. 优化了空穴传输层和磷光染料的掺杂浓度, 得到最佳发光效率的器件. 蓝光、黄光和红光器件的最大外量子效率为17.3%, 10.7% 和7.3%. 在发光亮度为1000 cd/m² 时, 蓝光、黄光和红光器件的外量子效率分别为17.0%, 10.6% 和5.8%, 器件效率下降较小. 原因在于同时采用空穴传输型和电子传输型的小分子材料作为共同主体材料, 器件具有较宽的载流子复合区域, 降低了三线激发态-三线激发态湮灭和三线激发态-极化子相互作用对器件发光效率的影响. 白光器件在亮度为1000 cd/m²时, 发光效率和功率效率为31 cd/A和 14.8 lm/W. 器件的色度为(0.32, 0.42), 色度比较稳定, 随电流的变化微小. 器件的效率较以往报道的有机-无机复合发光器件有显著的提高, 主要归因于在聚乙烯亚胺上能够制备特性良好的小分子材料薄膜, 以及小分子主体材料拥有较高的三线态能量和平衡的载流子传输特性, 能够获得高效的磷光发射.     

基于mCP与UGH2为母体的双发光层高效率蓝色磷光OLED

以9,9'-(1,3-苯基)二-9H-咔唑(m CP)和1,4-二(三苯甲硅烷基)苯(UGH2)为母体,将常用的蓝光染料二(3,5-二氟-2-(2-吡啶)苯基-(2-吡啶甲酸根))合铱(Ⅲ)(FIrpic)掺入这两种母体材料中,制得具有双发光层结构的蓝色磷光有机电致发光器件,并对整个物理机制进行了阐述。该器件较基于m CP或UGH2为母体的单发光层器件有着更高的器件效率。器件的最大电流效率、功率效率、外量子效率分别为21.13 cd/A、14.97 lm/W、10.56%。器件亮度从100 cd/m2到3 000 cd/m2时,效率滚降为34.2%。     

基于量子阱结构的混合型白光有机发光器件

以荧光材料BePP2结合量子阱作为蓝光发射层,磷光材料GIrl和R-4B掺入到混合双极性主体材料CBP∶Bphen中分别作为绿、红发光层并且在红绿发光层中引入间隔层TPBI,组合得到发白光的混合型有机发光器件。其中量子阱是以BePP2作为势阱、TCTA为势垒。结果表明:当势垒层数为2时,器件的最大发光亮度和电流效率分别为21 682.5 cd/m2和23.73 cd/A;当电压从7 V增加到14 V时,色坐标从(0.345,0.350)变化到(0.340,0.342)。与无量子阱结构的参考器件相比,势垒层数为2的器件的最大功率效率为8.07 lm/W,色坐标变化相对最小为±(0.005,0.008),还有一个高的显色指数83。     

光谱稳定的互补色双发光层高效混合白光OLED（英文）

利用两种颜色的发光层制备了光谱稳定的高效混合WOLED。其中蓝光发光层用14%质量分数的BNE掺杂在BePP_2中,橙光发光层用1%质量分数的Ir(bt)2(acac)掺杂在49.5%质量分数的NPB和49.5%质量分数的BePP_2组成的混合主体中。在不利用任何光耦合技术的条件下,器件在亮度为100 cd/m2时,功率效率可以达到39 lm/W;当亮度提高到1 000 cd/m~2时,效率仅发生轻微滚降至27.5 lm/W。器件的光谱稳定,亮度在1 000 cd/m~2和10 000 cd/m~2时,CIE坐标分别为(0.37,0.48)和(0.37,0.47)。良好的光谱稳定性归结于设计的双极性中间层平衡了其两侧激子的产生。     

TCTA对红绿磷光有机电致发光器件发光层激子的调控作用

制备了结构为ITO/MoO3(50 nm)/NPB(40 nm)/TCTA(10 nm)/CBP:14%GIr1(30 nm)/TCTA(x)/CBP:2%R-4B(10 nm)/BCP(10 nm)/Alq3(40 nm)/LiF(1 nm)/Al(100 nm)的红绿磷光有机电致发光器件,GIr1和R-4B分别为红、绿磷光染料。通过在红绿间插入较薄间隔层TCTA的方法,调节载流子、激子在红绿发光层中的分布,并结合TCTA和BCP对发光层内载流子和激子的有效阻挡作用,研究了载流子调控层TCTA在不同厚度下对器件发光性能的影响。结果表明,TCTA为1 nm时,器件的发光性能得到了很好的提升。电压为6 V时,TCTA为1 nm器件的电流密度、亮度、最大电流效率分别为0.509 mA/cm2、69.91 cd/m2和13.72 cd/A,而TCTA为0 nm器件的电流密度、亮度、最大电流效率分别为1.848 mA/cm2、215.7 cd/m2和11.67 cd/A。     

基于量子阱结构的高效磷光有机电致发光器件

采用多重量子阱结构制作了高效红色磷光有机电致发光器件。以4,4'-bis(N-carbazolyl)-1,10-biphenyl (CBP)掺杂bis(1-phenyl-isoquinoline)(Acetylacetonato) iridium(Ⅲ) (Ir(piq)₂(acac))为发光层,4,4'-bis(N-carbazolyl)-1,10-biphenyl(Bphen)为电荷控制层,形成了Ⅱ型双量子阱结构,器件的最大亮度为15 000 cd/m²,最大电流效率为7.4 cd/A,相对于参考器件提高了21%。研究结果表明:以Bphen为电荷控制层形成的Ⅱ型多重量子阱结构能有效地将载流子和激子限制在势阱中,并且使空穴和电子的注入更加平衡,从而提高了载流子复合的几率和器件的效率。     

Highly efficient all phosphorescent white organic light-emitting diodes for solid state lighting applications

We report highly efficient all phosphorescent white organic light-emitting diodes (OLEDs) with an exciton-confinement structure. By stacking two emissive layers (EMLs) with different charge transporting properties, effective charges as well as exciton confinements were achieved. Accordingly, efficient blue OLEDs with a peak external quantum efficiency (EQE) over 22% and power efficacy (PE) over 50 lm/W were developed by using iridium(III) bis(4,6-(difluorophenyl) pyridinato-N,C2′)picolinate (FIrpic) as an electro-phosphorescent dopant. When the optimized orange and red EMLs were sandwiched between the stacked two blue EMLs, white OLEDs with an EQE and PE of 24.3% and 45.9 lm/W at a luminance of 1000 cd/m² were obtained without the use of any out-coupling techniques. In addition, these white OLEDs exhibit a color rendering index (CRI) value of 84 with high efficacy.     

Bright white light electroluminescent devices based on efficient management of singlet and triplet excitons

Efficient and bright white organic light-emitting devices (WOLEDs) based on phosphor sensitized fluorescence are improved by using an unusual device structure, in which phosphorescent emissive layer is sandwiched between two blue fluorescent doped ones. This architecture allows for resonant energy transfer from both the host singlet and triplet energy levels that minimizes exchange energy losses. Thus, a WOLED with a maximum luminous efficiency of 11.63 cd/A, a maximum power efficiency of 7.37 lm/W, a maximum luminance of 31,770 cd/m², and Commission Internationale de L’Eclairage coordinates of (0.34, 0.36) is achieved.     

Non-doped phosphorescent white organic light-emitting devices with a quadruple-quantum-well structure

Non-doped white organic light-emitting devices (WOLEDs) with a quadruple-quantum-well structure were fabricated. An alternate layer of ultrathin blue and yellow iridium complexes was employed as the potential well layer, while potential barrier layers (PBLs) were chosen to be 2,2',2''-(1,3,5-benzenetriyl)-tris(1-phenyl-1-H-benzimidazole) (TPBi) or N,N'-dicarbazolyl-3,5-benzene (mCP) combined TPBi. On adjusting the PBLs for device performance comparison, the results showed that the device with all-TPBi PBLs exhibited a yellow emission with the color coordinates of (0.50,0.47) at a luminance of 1000 cd/m², while stable white emission with the color coordinates of (0.36,0.44) was observed in the device using mCP combined TPBi as the PBLs. Meanwhile, for the WOLED, with a reduced efficiency roll-off, a maximum luminance, luminous efficiency, and external quantum efficiency of 12,610 cd/m², 10.2 cd/A, and 4.4%, respectively, were achieved. The performance improvement by the introduction of mCP PBL was ascribed to the well confined exciton and the reduced exciton quenching effect in the multiple emission regions.     

高效、色度稳定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(white organic light-emitting diodes,WOLEDs)因可与有源驱动电路结合实现大开口率和高分辨率,因而在白光照明和全彩显示中有着良好的应用前景．本文制备了红/蓝双磷光发光层的顶发射WOLEDs,通过在红光层与蓝光层间插入电子阻挡层tris(phenypyrazole)iridium(Ir(ppz)₃),降低了对红光掺杂浓度的要求,红光掺杂浓度的提高不仅降低了对制备工艺的要求,提高了工艺可重复性,而且改善了WOLEDs的效率与色度稳定性。分析了色度稳定的原因,优化了红光和蓝光磷光客体的掺杂浓度,制备出发光效率达到7.9 cd·A-1的顶发射WOLED,其色坐标位于暖白光区,在87～2 402 cd·m-2亮度范围内色度很稳定,仅变化(0.006,0.01)。     

High-efficiency organic light-emitting diodes based on ultrathin blue phosphorescent modification layer

Yellow organic light-emitting devices(YOLEDs) with a novel structure of ITO/MoO_3(5 nm)/NPB(40 nm)/TCTA(15 nm)/CBP:(tbt)_2Ir(acac)(x%)(25 nm)/FIrpic(y nm)/TPBi(35 nm)/Mg:Ag are fabricated. The ultrathin blue phosphorescent bis[(4,6-difluorophenyl)-pyridi-nato-N,C2■](picolinate) iridium(Ⅲ)(FIrpic) layer is regarded as a highperformance modification layer. By adjusting the thickness of FIrpic and the concentration of (tbt)_2Ir(acac), a YOLED achieves a high luminance of 41618 cd/m~2, power efficiency of 49.7 lm/W, current efficiency of 67.3 cd/A, external quantum efficiency(EQE) of 18%, and a low efficiency roll-off at high luminance. The results show that phosphorescent material of FIrpic plays a significant role in improving YOLED performance. The ultrathin FIrpic modification layer blocks excitons in EML. In the meantime, the high triplet energy of FIrpic(2.75 eV) alleviates the exciton energy transport from EML to FIrpic.     

A study on the characteristics of OLEDs using Ir complex for blue phosphorescence

Several iridium-based complexes were investigated as phosphorescent dopants. They achieved about 100% internal quantum efficiency, due to utilization of both singlet and triplet excitons in the radiative processes. We have fabricated phosphorescent OLEDs with 8% Ir(ppz)₃ as a triplet emissive dopant in various host materials. CBP, which has an efficiency of 0.20 cd/A, is the best host material. Furthermore, we synthesized metal-organic phosphor complexes based on Ir with different ligands as to (Im)₂Ir(acac), (Im-R)₂Ir(acac), and Ir(ppz)₂(acac).     

High-efficiency blue and white phosphorescent organic light-emitting devices

We have significantly improved the efficiency of blue and white phosphorescence from organic light-emitting devices (OLEDs) based on phosphorescent iridium complexes. To improve the emission efficiency, 4,4^′-Bis(9-carbazolyl)-2,2^′-Dimethyl-biphenyl (CDBP), which has a high triplet energy, was used as the carrier-transporting host for the emissive layer. The blue phosphorescent OLED exhibited a maximum external quantum efficiency of 10.4%, which corresponds to a current efficiency of 20.4 cd/A. This result can be explained as due to the efficient confinement of triplet energy on blue phosphorescent molecules, which is consistent with the results of transient photoluminescence experiments. The white phosphorescent OLED with greenish-blue and red emissive layers exhibited a maximum external quantum efficiency of 12% and a luminous efficiency of 18 cd/A. This is primarily attributed to the improvement of greenish-blue emission efficiency as well as the emission efficiency of the blue phosphorescent OLED.     

Combined host–guest doping and host-free systems for high-efficiency white organic light-emitting devices

Highly efficient white organic light-emitting devices (WOLEDs) with a four-layer structure were realized by utilizing phosphorescent blue and yellow emitters. The key concept of device construction is to combine host–guest doping system of the blue emitting layer (EML) and the host-free system of yellow EML. Two kinds of WOLEDs incorporated with distinct host materials, namely N,N'-dicarbazolyl-3,5-benzene (mCP) and p-bis(triphenylsilyly)benzene (UGH2), were fabricated. Without using light out-coupling technology, a maximum current efficiency (η_C) of 58.8 cd/A and a maximum external quantum efficiency (η_EQE) of 18.77% were obtained for the mCP-based WOLED; while a maximum η_C of 65.3 cd/A and a maximum η_EQE of 19.04% were achieved for the UGH2-based WOLED. Meanwhile, both WOLEDs presented higher performance than that of conventionally full-doping WOLEDs. Furthermore, systematic studies of the high-efficiency WOLEDs were progressed.