利用Ir(ppy)_3敏化CzHQZn提高OLED的性能

用CzHQZn作为受主,利用磷光敏化的方法制备了有机电致黄光和白光器件。黄光器件采用Ir(ppy)3掺杂4,4-N,N′-=咔唑基联苯(CBP),敏化新的黄光材料CzHQZn作为发光层,当发光层厚度为18nm时器件性能最好,最大发光效率为3.26cd/A(at10V),最大发光亮度为17560cd/m2(at10V);白光器件采用多发光层结构,结合ADN的蓝光复合发光,同时加入了电子阻挡层(NPBX)和空穴阻挡层(BCP),获得的白光器件最大发光效率为2.94cd/A(at8V),最大亮度为11089cd/m2(at13V)。     

电子传输层中掺杂Ir(ppy)_3改善白光OLED的效率

采用真空热蒸镀技术,制备了结构为ITO/NPBX(40nm)/rubrene(0.2 nm)/NPBX(5nm)/DPVBi(30nm)/TPBi:x%Ir(ppy)3(30nm)/LiF/Al的白光器件。利用Ir(ppy)3掺杂到电子传输层TPBi中,在掺杂层中提高了电子的迁移率,调整了空穴和电子的平衡,从而改善了白色有机电致发光器件的效率。当Ir(ppy)3的掺杂浓度为6%时,器件的电流效率最高,在驱动电压9 V时最大电流效率为10.66 cd/A,此时色坐标为(0.36,0.38);当电子传输层TPBi中不掺杂Ir(ppy)3时,白光器件的效率最低,在驱动电压10V时最大电流效率为1.69 cd/A,此时色坐标为(0.31,0.30)。掺杂浓度为6%的白光器件的电流效率是不掺杂白光器件的电流效率的6.3倍。     

基于FHQZn发光的色度稳定的有机白光器件

研究了一种新型发光材料(E)-2-(2-(9H-fluoren-2-yl)vinyl)quinolato-Zinc的发光性能,利用它的空穴传输和发光特性制备了有机白光器件,器件的结构为:ITO/2T-NATA(15nm)/FHQZn(38nm)/NPB(25nm)/BCP(10nm)/Alq(30nm)/LiF(0.5nm)/Al,其中,(E)-2-(2-(9H-fluoren-2-yl)vinyl)quinoato-Zinc(FHQZn)作为空穴传输层和黄橙色发射层,N,N′-bis-(1-naphthyl)-N,N′-diphenyl-1,1′-biphenyl-4,4′-diamine(NPBX)作为蓝光发射层。器件最大的电流效率为1.68cd/A(at7V),最大的亮度为4624cd/m2(at12V),此时色坐标为(0.28,0.25)。器件的色坐标由7V(66.83cd/m2)时的(0.27,0.29)到12V(4624cd/m2)时的(0.28,0.25)几乎不变,是一个基于新型材料的色度较稳定的有机白光器件。     

基于TPAHQZn发光色度稳定的黄色OLED

采用一种既具有空穴传输特性又具有发光特性的新型荧光染料(E)-2-(4-(dipheny-lamino)styryl)quinolato-zinc (TPAHQZn)作为发光层,制备了结构为 ITO/ 4,4′,4″-{N,-(2-naphthyl)-N-phenylamino}-triphenylamine (2T-NATA)(15 nm)/ (E)-2-(4-(diphenylamino)styryl)quinolato-zinc (TPAHQZn)(x nm)/9,10-bis(2-naphthyl)anthracene(ADN)(31 nm)/ tris(8-quinolinolato) aluminum(Alq3)((65-x) nm)/LiF(0.6 nm)/Al的黄色有机电致发光器件.研究了不同厚度的发光层对器件性能的影响.TPAHQZn厚度为30 nm 的器件在14 V电压下实现了黄光发射,最大发光亮度为 2 479 cd/m2,最大电流效率为0.84 cd/A,色坐标由8 V(6.346 cd/m2)时的(0.502,0.449 5)到14 V(2 479 cd/m2 )时的(0.497 9,0.453)变化不大,器件的发光颜色稳定.     

通过引入电子阻挡层的高效率的有机磷光白光器件

以CBP作为母体材料,绿色磷光染料Ir(ppy)3作为敏化剂,以荧光染料rubrene作为受主,制备了结构为ITO/2T-NATA(25 nm)/ NPBX (25-d nm)/ CBP:5%Ir(ppy)3:0.5%Rubrene(8 nm)/NPBX(d nm)/DPVBi(30 nm)/TPBi(20 nm)/Alq(10 nm)/LiF(1 nm)/Al的白光器件.在器件中,敏化剂Ir(ppy)3、荧光染料rubrene的浓度分别为5.0 wt%和0.5 wt%,发光层的厚度选择8 nm,通过调整两层NPBX的厚度来改善器件的性能,得到了比较理想的白光发射.当d的厚度为10 nm 时,器件在7 V的电压下最大电流效率达到11.2 cd/A,在17 V的电压下其最大亮度达到28 170 cd/m2,色坐标为(0.37,0.42),处于白光区.     

基于CzHQZn发光的白光有机电致发光器件

利用一种新材料(E)-2-(2-(9-ethyl-9H-carbazol-3-yl)vinyl)quinolato-Zinc(CzHQZn)作空穴传输层和发光层制备了白光有机电致发光器件(WOLED),器件的结构为indium-tin oxide(ITO)/4,4′,4′′-{N,-(2-naphthyl)-N-phenylamino}-triphenylamine(2T-NATA)(22 nm)/CzHQZn(xnm)/N,N′-bis-(1-naphthyl)-N,N′-diphenyl-1,1′-biphenyl-4,4′-diamine(NPBX)(ynm)/2,9-dimethyl,-4,7-diaphenyl,1,10-phenanthroline(BCP)(10nm)/tris(8-quinolinolato)aluminum(Alq3)(68-x-ynm)/LiF(0.5 nm)/Al。研究发现发光层CzHQZn和NPBX的厚度对器件的发光性能有较大的影响。当CzHQZn厚度x为22 nm、NPBX厚度y为8 mm时,得到了色度最好和效率最大的WOLED,最大电流效率为0.9 cd/A(at ...     

通过Ir(ppy)3敏化黄光发射的白色有机电致发光器件

通过Ir(ppy)3的磷光敏化作用,制作了结构为:ITO/2T-NATA(20 nm)/NPBX(20 mm)/CPB∶x%Ir(ppy)3∶0.5%rubrene(8 nm)/NPBX(5 nm)/DPVBi(30 nm)/Alq(30 nm)/LiF(0.5 nm)/Al的有机白光器件.当Ir(ppy)3的掺杂浓度为6%时,器件的性能最好.在15 V的电压下最大亮度达到24 960 cd/m2,在电压为8 V的情况下,发光效率达到最大,为5.17 cd/A.该器件的色坐标在白光等能点附近,是色度较好的白光器件.     

CBP超薄层对有机电致磷光器件效率的影响

在空穴传输层(HTL)和发光层(EML)间插入4,4-N,N′-二咔唑基联苯(CBP)超薄层,制备了结构为ITO/NPB/CBP(xnm)/CBP:Ir(ppy)3/BCP/Alq3/LiF/Al有机电致磷光器件。与未插入CBP超薄层的器件相比,CBP超薄层的引入可以有效阻挡Ir(ppy)3的三线态能量通过Dexter能量转移到HTL的NPB中,减少无辐射能量损失,提高了器件发光效率。调整CBP薄层的厚度,当x为3nm时,器件的效率提高幅度最大,从x为0nm时的9.0cd/A提高到16.9cd/A。     

基于DPVBi发光的新结构有机白光器件

介绍了结构为ITO/4,4',4"-tris{N,-(3-methylphenyl)-N-phenylamino}tripheny-lamine(m-MTDATA,40 nm)/N,N'-diphenyl-N,N'-bis(1-naphthyl)-(1,1'-biphenyl)-4,4'-diamine(NPB,5 nm)/4,4'-bis(2,2'diphenyl vinyl)-1,1'-biphenyl(DPVBi,x nm)/5,6,11,12,-tetraphenylnaphthacene(Rubrene,0.5 nm)/DPVBi(20 nm)/tris(8-hydroxyquinoline)aluminum(Alq,45-x nm)/LiF(0.5 nm)/Al的白光器件.采用了2个DPVBi层中间夹1个Rubrene的薄层,这种结构充分利用了DPVBi的空穴阻挡特性和发光特性,有力地平衡了来自于DPVBi的蓝光和Rubrene的黄光,从而使器件发出性能较好的白光.器件保持第2层DPVBi的厚度为20 nm,第1层的DPVBi的厚度按照5、8、11和14 nm的规律进行变化,相应改变Alq的厚度,使得这两者的总厚度为45 nm保持不变.当第1层DPVBi的厚度是8 nm、Alq的厚度是37 nm和其它层的厚度保持不变时,在13 V的电压下,器件的最大亮度为18 710 cd/m2,对应的效率为2.06 cd/A,色坐标为(0.29,0.30),属于白光发射.     

电压对有机蓝光器件发光光谱的影响

介绍了结构为ITO/40 nm 4,4′,4″-tris[N,-(3-methylphenyl)-N-phenylamino]tripheny- lamine(m-MTDATA)/5 nm N,N′-bis-(1-naphthyl)-N,N′-diphenyl-1,1′-biphenyl-4,4′- diamine(NPB)/x nm 4,4-bis(2,2-diphenyl vinyl)-1,1-biphenyl(DPVBi)/y nm 6,11,12,- tetraphenylnaphthacene(Rubrene)/40 nm tris(8-hydroxyquinoline)aluminum(Alq)/0.5 nm LiF/Al的器件,其发光光谱的半峰宽在电压由2 V变为12 V时,由140 nm变为70 nm,器件发光的峰值波长由456 nm变为444nm的规律。半峰宽变窄是由于随着电压的升高,被Ru- brene俘获的电子获得了足够的能量,越过Rubrene层,在DPVBi中与注入的空穴形成激子而复合发光的概率的逐步增加所造成的。峰值波长蓝移是由于激子的形成区域随着电压的增加逐渐由DPVBi层移向NPB层造成的。器件峰值波长的这种变化对器件的色度改善有着很大的影响。     

White organic light-emitting devices based on fac tris（2- phenylpyridine） iridium sensitized 5,6,11,12-tetraphenylnap -hthacene

We have fabricated the white organic light-emitting devices （WOLEDs） based on 4,4＇ -bis（2,2 -diphenyl vinyl）-1,1＇ - biphenyl （DPVBi） and phosphorescence sensitized 5,6,11,12,-tetraphenylnaphthacene （rubrene）. The device structure is ITO/2T-NATA （20 nm）/NPBX （20 nm）/CBP： x%Ir（ppy）3：0.5% rubrene （8 nm）/NPBX （5 nm）/DPVBi （30 nm）/Alq（30 nm）/LiF（0.5 nm）/A1. In the devices, DPVBi acts as a blue light-emitting layer, the rubrene is sensitized by a phosphorescent material, fac tris （2-phenylpyridine） iridium [Ir（ppy）3], acts as a yellow light-emitting layer, and N,N＇ -bis- （1-naphthyl）- N,N＇ -diphenyl -1, 1＇ -biphenyl-4,4＇ -diamine （NPBX） acts as a hole transporting and exciton blocker layer, respectively. When the concentration of Ir （PPY）3 is 6wt%, the maximum luminance is 24960 cd/m^2 at an applied voltage of 15 V, and the maximum luminous efficiency is 5.17 cd/A at an applied voltage of 8 V.     

An organic light-emitting devices of highly efficient white phosphor using an electron/exciton blocker

Highly efficient white phosphorescent organic light-emitting devices （WOLEDs） was fabricated using an electron/exciton blocker. The device structure is ITO/2T-NATA（25 nm）/NPBX（25-dnm）/CBP：5%Ir（ppy）3：0.5%Rubrene（8 nm）/NPBX（dnm）/ DPVBi（30 nm）/TPBi（20 nm）/Alq（10nm）/LiF（1nm）/A1, in which N,N ＇ -bis- （1-naphthyl）- N,N ＇ -dipheny1-1, 1 ＇ - biphenyl-4,4 i -diamine （NPBX） functions as a hole transport layer and electron/exciton blocker, 4,4,N,N ＇ dicarbazolebiphenyl （CBP） is host, 4,4＇ -bis（2,2 -diphenyl vinyl）-1,1 ＇ -biphenyl （DPVBi） is blue fluorescent dye, 5,6,11, 12,-tetraphenylnaphthacene （rubrene） is fluorescent dye, factris （2-phenylpyridine） iridium （Ir（ppy）3） is phosphorescent sensitizer and tris（8-hydroxyquinoline） aluminum （Alq3） is an electron transport layer. The WOLEDs have obtained white light emission by adjusting the thickness of NPBX, when the concentration of Ir（ppy）3 is 5-wt% and rubrene is 0.5-wt%, respectively, the thickness of the doped emissive layer is 8 nm, the WOLEDs show a maximum luminous efficiency is 11.2 cd/ A with d of 10 nm at 7 V and a maximum luminance of 28170 cd/m^2 at 17 V, the CIE coordinates is （0.37.0.42）, which is in white region.     

(t-bt)2Ir(acac)超薄层厚度对有机电致发光器件性能的影响

以新型铱配合物黄光磷光染料bis[2-(4-tertbutylphenyl)benzothiazolato-N,C2']iridium(acetylacetonate)[(tbt)2Ir(acac)]为超薄层,制备了结构为indium tin oxide(ITO)/N,N'-bis(naphthalen-1-yl)-N...     

以CzHQZn为主体的有机发光器件的发光效率

采用真空热蒸镀技术,分别制备了结构为ITO/2T-NATA(25nm)/CzHQZn(10～25nm)/TPBi(35nm)/LiF(0.5nm)/Al、ITO/2T-NATA(30nm)/CBP:6%Ir(ppy)3:x%CzHQZn(20nm)/Alq3(50nm)/LiF(0.5nm)/Al和ITO/2T-NATA(30nm)/CBP:6%Ir(ppy)3:10%CzHQZn(xnm)/Alq3((70-x)nm)/LiF(0.5nm)/Al的3组有机电致发光器件(OLED)。器件中,CzHQZn既有空穴传输特性,又是黄光发射的主体。为了提高其发光效率,利用磷光敏化技术,研究了掺杂层中不同掺杂浓度和掺杂层不同厚度时器件的发光效率。结果表明,器件的效率随着掺杂发光层的厚度和掺杂浓度的变化而改变,当发光层的厚度为18nm时,CzHQZn掺杂浓度为10%的器件性能较好;在10V电压下,器件的最大电流效率达到3.26cd/A,色坐标为(0.4238,0.5064),最大亮度达到17560cd/m2。     

高效率磷光与荧光相结合的白色有机发光器件

制作了一种白色有机电致发光器件(WOLED)。将红光[Ir(piq)2(acac)]及绿光[Ir(ppy)3]磷光掺杂染料分别掺入到母体CBP中,在2种磷光发光层间插入蓝光材料DPVBi,引入电子传输能力强的BPhen作为电子注入层和空穴阻挡层,通过改变蓝光发光层的厚度,得到了高效率的WOLED,最大电流效率可达17.6cd/A,最大功率效率达13.7lm/W,最大亮度达27525cd/m2,当电压从4V变化到12V时,色坐标从(0.54,0.35)变化到(0.30,0.31),基本处于白光区。器件的特点在于DPVBi的存在阻挡了2种磷光材料间的能量转移,色度可以通过简单地调整DPVBi的厚度,避免使用稀有的蓝光磷光材料和与其相匹配的母体材料,同时又可以保持较高的发光效率。     

Improved hole-transporting properties of Ir complex-doped organic layer for high-efficiency organic light-emitting diodes

We have investigated the hole-transporting properties of three different Ir complexes doped 4,4′,4″-tri (N-carbazolyl) triphenylamine (TCTA) using a series of hole-only devices. The improvement of hole-transporting ability was depended on the species of Ir complexes and their doping concentrations. We attributed the improved performance to their strong electron-accepting abilities or hole-transfer capabilities. Yellow organic light-emitting diodes (OLEDs) based on bis(2-phenylbenzothiazolato)(acetylacetonate)iridium bt₂Ir(acac) were fabricated by utilizing this method with optimized doping concentration. The best electroluminescent (EL) performance of maximum 83.6 lm/W was obtained for the yellowing-emitting OLED by doping of Firpic into TCTA hole transport layer, compared with the cases of doping of Ir(ppy)₃ into TCTA and doping of Ir(bpiq)₂acac into TCTA. Moreover, the turn-on voltage of device decreased to 2.2 V, which was corresponding to the optical band gap of the emitter.     

Efficient nondoped organic light-emitting diodes with Cu complex emitter

In Cu^I complex based organic light emitting diodes (OLEDs) a host matrix is traditionally thought to be required to achieve high efficiency. Herein, it is found that the device ITO/MoO₃ (1 nm)/4,4′-N,N′-dicarbazole-biphenyl (CBP, 35 nm)/[Cu(μ-I)dppb]₂ (dppb = 1,2-bis[diphenylphosphino]benzene, 20 nm)/1,3,5-tris(N-phenylbenzimidazole-2-yl)benzene (TPBi, 65 nm)/LiF (1 nm)/Al (100 nm) with a vacuum thermal evaporated nondoped Cu^I complex emissive layer (EML) showed external quantum efficiency and current efficiency of 8.0% and 24.3 cd/A at a brightness of 100 cd/m², respectively, which are comparable to the maximum efficiencies reported in an optimized doped OLED with the same emitter, higher efficiency than the OLED with a [Cu(μ-I)dppb]₂:CBP EML, and much higher efficiencies than the nondoped OLED with a bis(2-phenylpyridine)(acetylacetonate)iridium [Ir(ppy)₂(acac)] EML. A series of reference films and single carrier devices were fabricated and studied to understand the difference between Cu^I and Ir^III complex based nondoped OLEDs.