同时掺杂磷光和荧光染料的白色有机电致发光器件性能研究

以磷光染料Ir(piq)₂(acac)作为发光掺杂剂,掺入空穴传输性主体材料NPB中得到红色发光层,荧光材料TBP掺入到主体CBP中作为蓝色发光层,制备了结构为ITO/NPB/NPB：Ir(piq)₂(acac)/CBP/CBP：TBPe/BCP/ALq/Mg：Ag的双发光层白色有机电致发光器件.其中ALq₃、未掺杂的NPB和CBP及BCP层分别作为电子传输层、空穴传输层和激子阻挡层.实验中通过调节发光层厚度及Ir(piq)_{2关键词： 磷光 激子阻挡层 有机电致发光}     

不同主体双发光层白色有机电致发光器件的性能研究

制备了结构为ITO/NPB/CBP:TBPe:rubrene/BAlq:Ir(piq)₂(acac)/BAlq/Alq₃/Mg:Ag的白色磷光有机电致发光器件.利用两种不同的主体材料,即用双载流子传输型主体材料CBP掺杂荧光染料TBPe及rubrene作为蓝光和橙黄光发光层;用电子传输型主体材料BAlq掺杂磷光染料Ir(piq)₂(acac)作为红色发光层.以上双发光层夹于空穴传输层NPB与具有电子传输性的阻挡层BALq之间.讨论了如何控制 关键词： 有机电致发光 磷光染料 掺杂 白光     

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.     

一种多层白色磷光有机电致发光器件的制备及性能研究

制备了一种结构为ITO/NPB/NPB:Ir(piq)₂(acac)/CBP:TBPe/BAlq:rubrene/BAlq/Alq₃/Mg:Ag的白色磷光有机电致发光器件.其中空穴传输型主体NPB掺杂磷光染料Ir(piq)₂(acac)作为红色发光层,双载流子传输型主体4,4′-N,N′-dicarbazole-biphenyl (CBP)掺杂TBPe作为蓝色发光层,电子传输型主体材料BAlq掺杂rubrene作为绿色发光层.以上发光层夹于 关键词： 电致发光 磷光染料 异质结 白光     

不同主体双发光层白色有机电致发光器件的性能研究

制备了结构为ITO/NPB/CBP:TBPe:rubrene/BAlq:Ir(piq)₂(acac)/BAlq/Alq₃/Mg:Ag的白色磷光有机电致发光器件.利用两种不同的主体材料,即用双载流子传输型主体材料CBP掺杂荧光染料TBPe及rubrene作为蓝光和橙黄光发光层;用电子传输型主体材料BAlq掺杂磷光染料Ir(piq)₂(acac)作为红色发光层.以上双发光层夹于空穴传输层NPB与具有电子传输性的阻挡层BALq之间.讨论了如何控制     

基于CBP:BCzVB:Btp2Ir(acac)体系的白色有机电致发光器件色度飘移研究

以苯乙烯类化合物BCzVB为蓝色荧光染料,以铱配合物Btp_2Ir(acac)为红色磷光染料,共掺杂到CBP基质中作为发光层,制备了白色有机电致发光器件,研究了该体系发光色度漂移的原因。器件在掺杂CBP:6?zVB: 0．2%Btp_2Ir(acac),在．驱动电流从4～200 mA/cm~2变化范围内,发光色坐标从(0．340,0．273)飘移到(0．308, 0．273),色坐标轻微蓝移。对器件发光光谱和亮度-电流密度曲线等分析表明:器件色度的轻微蓝移是由于CBP基质向Btp_2Ir(acac)掺杂剂完全的能量传递、荧光染料BCzVB向磷光染料Btp_2Ir(acac)不完全的能量传递等内在物理过程和磷光染料Btp_2Ir(acac)自身发光饱和等特性共同决定的。     

磷光铱配合物的纯度对其电致发光性能的影响

采用不同的真空热梯度升华条件,获得了不同纯度的乙酰丙酮酸二(2-苯基吡啶)铱Ir(ppy)₂(acac)。以不同纯度Ir(ppy)₂(acac)为客体材料,制备了结构为ITO:MoO₃/CBP/CBP:Ir(ppy)₂(acac)/TPBi/LiF:Al的有机发光二极管(OLEDs),其中CBP和TPBi分别是4,4'-二(9-咔唑)联苯和1,3,5-三(1-苯基-1H-苯并咪唑-2-基)苯。评价了不同纯度磷光铱配合物制备的器件的电致发光性能,探索了磷光铱配合物纯度对器件性能的影响。结果表明:Ir(ppy)₂(acac)升华后可以提高器件的稳定性,纯度高的材料可以在较低的掺杂浓度下获得较高的发光效率。     

两种磷光材料在聚合物掺杂体系中的发光特性研究

磷光材料由于可以利用电致激发所形成的单重态和三重态激子,因而可以得到接近100%的内量子效率。文章对常温下基于磷光材料Ir(ppy)₃及Ir(piq)₃掺杂PVK薄膜为发光层的器件的光学和电学特性进行了研究。光致发光的结果显示相同掺杂质量比下由PVK到Ir(piq)₃的能量传递比到Ir(ppy)₃更加困难。通过研究两种掺杂体系不同质量比的电致发光特性,可以认为这两种磷光器件的发光主要来自于磷光客体分子直接俘获载流子发光而非主体的能量传递。Ir(piq)₃掺杂体系对掺杂比例的依赖更为明显,从能级结构分析,认为是由于Ir(piq)₃的更低的HOMO及高的LUMO能级,而比Ir(ppy)₃具有更好的载流子俘获和传输特性。     

基于PVK的高色纯度高稳定性有机电致红光器件

利用旋涂法和真空蒸镀法相结合的方法,根据能量空间传递的原理制备了PVK ∶ Ir(piq)₂(acac)体系的红色有机电致发光显示器件。器件的结构为ITO/CuPc/PVK ∶ Ir(piq)₂(acac)/BCP/Alq₃/LiF/Al。研究了不同主客体掺杂比对器件发光性能的影响,得到了高色纯度、单色性较好的红光器件。当Ir(piq)₂(acac)掺杂的质量比为1 ∶ 0.08时,器件的综合性能达到最佳,发光峰位于625 nm,CIE坐标为(x=0.66,y=0.33)。通过对各层厚度的合理选择,形成相对优化的微腔结构,充分利用其对光谱的窄化效应,使得器件的EL光谱的发射半峰全宽仅为55 nm,提高了器件的发光性能。器件光谱具有很好的单色性,色纯度达到98.2%。     

新型双色有机电致磷光器件

所研究的有机电致磷光发光器件(OLED)选用了一种新型金属铱的化合物Ir(C6)₂(acac),这种金属化合物由配位体香豆素C6和乙酰丙酮(acac)与金属铱化合形成。Ir(C6)₂(acac)可同时作为电子传输材料和发光掺杂剂。比较香豆素C6和Ir(C6)₂(acac)固体材料的光致发光谱,可见Ir(C6)₂(acac)明显抑制了有机电致发光材料分子与分子之间的发光猝灭效应。采用ITO/TPD(N,N′-diphenyl-N,N′-bis(3-methyl-phenyl)-1,1′biphenyl-4,4′diamine)/Ir(C6)₂(acac)/BAlq(bis(2-methyl-8-quinolinolato-N₁,O₈)-(1,1′-biphenyl-4-olato)aluminum)/Alq₃aluminum/Liq(8-hydroxyquinolinelithium)/Al结构,可得到CIE(Commission Interationaled′Eclairage)值为x=0.43;y=0.40的橙红色发光器件,最高亮度可达3390cd/m₂,最大电流效率为1.3cd/A。采用同样的器件结构以Ir(C6)₂(acac)掺杂Alq₃主体得到绿色发光器件,发光色的CIE坐标值为x=0.29;y=0.58,最高亮度可达8832cd/m₂,最大电流效率为5.6cd/A。器件的发光机理研究表明Ir(C6)₂(acac)的非掺杂器件发光以Ir(C6)₂(acac)的三线态磷光为主,器件发光为橙色;在Alq₃中的单掺杂器件以Alq₃和Ir(C6)₂(acac)的荧光为主,同时有小比例Ir(C6)₂(acac)的三线态磷光成分存在,器件总体发光为绿色。     

新型有机电致磷光白光器件的研究

制备了结构为ITO/NPB/TCTA/FIrpic∶TCTA/Ir(MDQ)2(acac)∶TmPyPB/FIrpic∶TmPyPB/TmPyPB/LiF/Al的有机电致磷光发光器件。通过在双蓝光发光层之间插入较薄的红光层Ir(MDQ)2(acac)∶TmPyPB调节载流子、激子在各发光层中的分布,并结合TCTA和TmPyPB对发光层内载流子和激子的有效阻挡作用,混合实现白光发射。研究了红光层在不同厚度、不同掺杂浓度下对器件发光性能的影响。结果表明,红光发光层厚度为2nm、质量浓度为5%时,结合蓝光发光层和红光发光层,实现了色坐标为(0.333,0.333)、最大发光效率为11.50cd/A的白光发射。     

Study of different roles phosphorescent material played in different positions of organic light emitting diodes

Phosphorescent materials are crucial to improve the luminescence and efficiency of organic light emitting diodes (OLED), because its internal quantum efficiency can reach 100%. So the studying of optical and electrical properties of phosphorescent materials is propitious for the further development of phosphorescent OLED. Phosphorescent materials were generally doped into different host materials as emitting components, not only played an important role in emitting light but also had a profound influence on carrier transport properties. We studied the optical and electrical properties of the blue 4,4′-bis(2,2-diphenylvinyl)-1,1′-biphenyl (DPVBi)-based devices, adding a common yellow phosphorescent material bis[2-(4-tert-butylphenyl)benzothiazolato-N,C2′] iridium(acetylacetonate) [(t-bt)₂Ir(acac)] in different positions. The results showed (t-bt)₂Ir(acac) has remarkable hole-trapping ability. Especially the ultrathin structure device, compared to the device without (t-bt)₂Ir(acac), had increased the luminance by about 60%, and the efficiency by about 97%. Then introduced thin 4,4′-bis(carbazol-9-yl)biphenyl (CBP) host layer between DPVBi and (t-bt)₂Ir(acac), and got devices with stable white color.     

Electroluminescence of organic light-emitting diodes consisting of an undoped (pbi)2Ir(acac) phosphorescent layer

The electroluminescence (EL) characteristics of phosphorescent organic light-emitting diodes (OLEDs) with an undoped bis(1,2-dipheny1-1H-benzoimidazole) iridium (acetylacetonate) [(pbi)₂Ir(acac)] emissive layer (EML) of various film thicknesses were studied. The results showed that the intensity of green light emission decreased rapidly with the increasing thickness of (pbi)₂Ir(acac), which was relevant to the triplet excimer emission. It suggested that the concentration quenching of monomer emission in the undoped (pbi)₂Ir(acac) film was mainly due to the formation of triplet excimer and partly due to the triplet-triplet annihilation (TTA) and triplet-polaron annihilation (TPA). A green OLED with a maximum luminance of 26,531 cd/m², a current efficiency of 36.2 cd/A, and a power efficiency of 32.4 lm/W was obtained, when the triplet excimer emission was eliminated. Moreover, the white OLED with low efficiency roll-off was realized due to the broadened recombination zone and reduced quenching effects in the EML when no electron blocking layer was employed.     

不同主体材料对红色磷光OLED器件性能的影响

制作了结构为ITO/2T-NATA (20 nm)/NPB(60 nm)/Zn(BTZ)₂ : Ir(DBQ)₂(acac) (80 nm)/Alq₃(70 nm)/LiF(1 nm)/Al(200 nm)的红光器件,其中2T-NATA是4,4',4″-tris(N-(2-naphthyl)-N-phenyl-amino)-triphenylamine,NPB是N,N'-di(naphthalen-1-yl)-N,N'-diphenyl-benzidine, Zn(BTZ)₂是Bis-(2-(2-hydroxyphenyl) benzothiazole)zinc,Ir(DBQ)₂(acac)是iridium complex,Alq₃ 是tris(8-hydroxyquinolato)aluminum。基于Ir(DBQ)₂(acac) 掺杂的Zn(BTZ)₂体系的器件给出最高电致发光(EL)性能。结果显示:10％Ir(DBQ)₂-(acac) 掺杂Zn(BTZ)₂器件的亮度和效率分别为25 000 cd/m²和12 cd/A,其相应的EL峰位于620 nm,色坐标(x=0.63,y=0.37)。由于未使用激子阻挡层,所以,比通常磷光器件的制作工艺简单并且操作过程容易控制。     

ITO‐free top emitting organic light emitting diodes with enhanced light out‐coupling

Bottom emitting organic light emitting diodes (OLEDs) can suffer from lower external quantum efficiencies (EQE) due to inefficient out‐coupling of the generated light. Herein, it is demonstrated that the current efficiency and EQE of red, yellow, and blue fluorescent single layer polymer OLEDs is significantly enhanced when a MoO_x(5 nm)/Ag(10 nm)/MoO_x(40 nm) stack is used as the transparent anode in a top emitting OLED structure. A maximum current efficiency and EQE of 21.2 cd/A and 6.7%, respectively, was achieved for a yellow OLED, while a blue OLED achieved a maximum of 16.5 cd/A and 10.1%, respectively. The increase in light out‐coupling from the top‐emitting OLEDs led to increase in efficiency by a factor of up to 2.2 relative to the optimised bottom emitting devices, which is the best out‐coupling reported using solution processed polymers in a simple architecture and a significant step forward for their use in large area lighting and displays.     

Novel Field Emission Organic Light Emitting Diodes with Dynode

This work presents novel field emission organic light emitting diodes(FEOLEDs) with dynode,in which an organic EL light-emitting layer is used instead of an inorganic phosphor thin film in the field emission display(FED).The proposed FEOLEDs introduce field emission electrons into organic light emitting diodes(OLEDs),which exhibit a higher luminous efficiency than conventional OLED.The field emission electrons emitted from the carbon nanotubes(CNTs) cathode and to be amplified by impact the dynode in vacuum.These field emission electrons are injected into the multi-layer organic materials of OLED to increase the electron density.Additionally,the proposed FEOLED increase the luminance of OLED from 10 820 cd/m2 to 24 782 cd/m2 by raising the current density of OLED from an external electron source.The role of FEOLED is to add the quantity of electrons-holes pairs in OLED,which increase the exciton and further increase the luminous efficiency of OLED.Under the same operating current density,the FEOLED exhibits a higher luminous efficiency than that of OLED.     

用于光通信的高速响应有机电致发光器件

采用直接光强调制的方法,建立了一种新型有机电致发光器件(OLED)的光电信号传输体系,研究了发光层掺杂、发光面积和预置电压对OLED响应速度的影响。结果发现:与发光层为单独的Alq3的器件相比较,掺杂rubrene的发光层的荧光寿命较短,响应较快;减小OLED的发光面积能提高OLED的响应速度,并在0.02 mm2的发光面积上实现了100 Mbit/s的信号传输速度;同时,预置直流电压也能改善OLED的响应速度。最后,提出将柔性OLED与聚合物波导及有机光电二极管结合,实现了一种全有机的柔性光电子体系。