混合蓝色和绿色发射的高亮度白色有机电致发光器件

使用星形六苯芴类新材料1,2,3,4,5,6-hexakis(9,9-diethyl-9H-fluoren-2-y1)benzene(HKEthFLYPh)分别制备了三种不同结构的有机电致发光器件.在结构为indium-tin oxide(ITO)/NPB(40nm)/HKEthFLYPh(10nm)/Alq3(50nm)/Mg:Ag(200nm)的器件中,获得了两个电致发光谱峰分别位于435和530nm处的明亮白光.HKEthFLYPh足能量传输层;N,N'-bis-(1-naphthyl)-N,N'-diphenyl-(1,1'-biphenyl)-4,4'-diamine(NPB)是空穴传输层和蓝色发光层;tris(8-hydroxyquinoline)aluminum(Alq3)是电子传输层和绿色发光层.结果表明,当驱动电压为15V时,器件的最大亮度达到8523cd·m-2;在5.5V时,器件达到最大流明效率为1.01m·W-1.在电压为9V时,CIE色坐标为(0.29,0.34).此外,通过改变HKEthFLYPh层的厚度,发现蓝色发射的相对强度随着HKEthFLYPh层厚度的增加而增强.     

混合蓝色和绿色发射的高亮度白色有机电致发光器件

使用星形六苯芴类新材料1,2,3,4,5,6-hexakis(9,9-diethyl-9H-fluoren-2-yl)benzene (HKEthFLYPh)分别制备了三种不同结构的有机电致发光器件. 在结构为indium-tin oxide (ITO)/NPB (40 nm)/HKEthFLYPh (10 nm)/Alq3(50 nm)/Mg:Ag (200 nm)的器件中, 获得了两个电致发光谱峰分别位于435 和530 nm处的明亮白光. HKEth-FLYPh是能量传输层; N,N’-bis-(1-naphthyl)-N,N’-diphenyl-(1,1’-biphenyl)-4,4’-diamine (NPB)是空穴传输层和蓝色发光层; tris(8-hydroxyquinoline)aluminum (Alq3)是电子传输层和绿色发光层. 结果表明, 当驱动电压为15 V时, 器件的最大亮度达到8523 cd·m-2; 在5.5 V时, 器件达到最大流明效率为1.0 lm·W-1. 在电压为9 V时, CIE色坐标为(0.29, 0.34). 此外, 通过改变HKEthFLYPh层的厚度, 发现蓝色发射的相对强度随着HKEthFLYPh层厚度的增加而增强.     

Bright White Organic Light-Emitting Diode Mixed Blue and Green Emission

Double-layer and triple-layer organic light-emitting diodes (OLEDs) were fabricated using a novel star-shaped hexafluorenylbenzene organic material, 1,2,3,4,5,6-hexakis(9,9-diethyl-9H-fluoren-2-yl)benzene (HKEthFLYPh) as an energy transfer layer, N, N′-bis-(1-naphthyl)-N, N′-diphenyl-(1,1′-biphenyl)-4,4′-diamine (NPB) as a hole-transport layer (HTL) and blue emissive layer (EML), and tris(8-hydroxyquinoline)aluminum (Alq₃) as an electron-transport layer (ETL) and green light-emitting layer. Bright white light was obtained with a triple-layer device structure of indium-tin-oxide (ITO)/NPB (40 nm)/HKEthFLYPh (10 nm)/Alq₃ (50 nm)/Mg:Ag (200 nm). A maximum luminance of 8523 cd·m⁻² at 15 V and a power efficiency of 1.0 lm·W⁻¹ at 5.5 V were achieved. The Commissions Internationale de L′Eclairage (CIE) coordinates of the device were (0.29, 0.34) at 9 V, which located in white light region. With increasing film thickness of HKEthFLYPh, light emission intensity from NPB increased compared to that of Alq₃.     

Highly Efficient Candlelight Organic Light-Emitting Diode with a Very Low Color Temperature

Low color temperature candlelight organic light-emitting diodes (LEDs) are human and environmentally friendly because of the absence of blue emission that might suppress at night the secretion of melatonin and damage retina upon long exposure. Herein, we demonstrated a lighting device incorporating a phenoxazine-based host material, 3,3-bis(phenoxazin-10-ylmethyl)oxetane (BPMO), with the use of orange-red and yellow phosphorescent dyes to mimic candlelight. The resultant BPMO-based simple structured candlelight organic LED device permitted a maximum exposure limit of 57,700 s, much longer than did a candle (2750 s) or an incandescent bulb (1100 s) at 100 lx. The resulting device showed a color temperature of 1690 K, which is significantly much lower than that of oil lamps (1800 K), candles (1900 K), or incandescent bulbs (2500 K). The device showed a melatonin suppression sensitivity of 1.33%, upon exposure for 1.5 h at night, which is 66% and 88% less than the candle and incandescent bulb, respectively. Its maximum power efficacy is 23.1 lm/W, current efficacy 22.4 cd/A, and external quantum efficiency 10.2%, all much higher than the CBP-based devices. These results encourage a scalable synthesis of novel host materials to design and manufacture high-efficiency candlelight organic LEDs.     

Nondoped-type White Organic Light-Emitting Diode Using Star-Shaped Hexafluorenylbenzene as an Energy Transfer Layer

White organic light-emitting diodes (WOLEDs) with a structure of indium-tin-oxide (ITO)/N,N'-bis-(1-naphthyl)-N,N'-diphenyl-(1,1'-biphenyl)-4,4'-diamine (NPB)/1,2,3,4,5,6-hexakis(9,9-diethyl-9H-fluoren-2-yl)benzene (HKEthFLYPh)/5,6,11,12 -tetraphenylnaphtacene (rubrene)/tris(8-hydroxyquinoline) aluminum (Alq3)/Mg:Ag were fabricated by vacuum deposition method, in which a novel star-shaped hexafluorenylbenzene HKEthFLYPh was used as an energy transfer layer, and an ultrathin layer of rubrene was inserted between HKEthFLYPh and Alq3 layers as a yellow light-emitting layer instead of using a time-consuming doping process. A fairly pure WOLED with Commissions Internationale De L'Eclairage (CIE) coordinates of (0.32, 0.33) was obtained when the thickness of rubrene was 0.3 nm, and the spectrum was insensitive to the applied voltage. The device yielded a maximum luminance of 4816 cd/m2 at 18 V.     

高效白色磷光有机电致发光器件

采用真空热蒸镀方法以4,4'-bis (carbazol-9-yl) biphenyl (CBP)为主体材料、以bis[2-(4-tert-butylphenyl) benzothiazolato-N,^C2] iridium (acetylacetonate) [(t-bt)₂Ir(acac)]磷光染料为掺杂剂构成黄色发光层, 制备了高效白光的有机电致发光器件(OLEDs). OLEDs的器件结构为indiumtin oxide (ITO)/N,N’-bis-(1-naphthyl)-N,N’-biphenyl-1,1’-biphenyl-4,4’-diamine (NPB)/CBP: (t-bt)₂Ir (acac)/NPB/2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP)/8-hydroxy quinoline aluminum(Alq₃)/Mg:Ag, 从ITO阳极开始的第一层NPB为空穴传输层, 第二层超薄的NPB为蓝色发光层, BCP为空穴阻挡层和激子阻挡层, Alq₃为电子传输层. 结果表明, 器件电压在3 V启亮, 在16.5 V时, 器件的最高亮度达到15460 cd·m^-2; 在4 V时, 器件达到最大流明效率为7.5 lm·W^-1, 器件启亮后所发出的白光光谱在低电压时随电压变化有稍微的移动, 但是都在白光范围内变化. 在电压达到8 V后Commission Internationale I’Eclairage(国际照明委员会) (CIE)色坐标为(0.33, 0.32), 并且光谱及色坐标稳定, 不随电压变化而改变, 与最佳的白光坐标(0.33, 0.33)几乎重合. 同时, 从机理上解释了光谱移动和效率衰减的原因, 并探讨了载流子陷阱和能量传递的关系.     

白光有机发光二极管的研究进展

由于白光有机发光二极管(WOLED)具有效率高、亮度高、功耗低、视角广、响应速度快、主动发光、超薄超轻以及可柔性化等优异性能, 并在显示和照明领域有广阔的应用前景, 受到学者和业界的广泛重视而成为研究热点. 本文首先介绍了实现WOLED的不同方法, 然后从发光材料种类的角度, 阐述了全荧光WOLED、全磷光WOLED、基于荧光/磷光杂化WOLED以及延迟荧光WOLED近年来的研究进展, 并结合我们研究团队最近的工作详细地介绍了不同高性能WOLED的器件结构、设计思想、工作原理、物理机制以及发光过程; 接着, 简单介绍了柔性WOLED最近研究进展; 最后探讨了WOLED目前存在的问题及其未来的发展趋势.     

白光有机电致发光器件进展

白光有机电致发光器件（WOLEDs）在显示和照明领域有着极大的应用前景,受到人们广泛的关注。本文从多个方面综述了WOLEDs近年来的研究进展,探讨了它的应用前景及需要解决的问题。     

抗菌医药左氧氟沙星在有机电致发光二极管中的应用

左氧氟沙星(LOFX)是一种知名的抗菌药物, 它的价格非常便宜, 且有成熟的合成和纯化技术. 本文中首次将LOFX作为一种蓝光发光材料和电子传输材料应用于有机电致发光器件(OLED)中. 通过热重分析、UVVis吸收光谱、发射光谱以及循环伏安曲线详细地表征了LOFX的热学及光物理特性. LOFX有高的分解温度,为327 ℃; HOMO、LUMO能级分别为-6.2 和-3.2 eV, 光学带隙为3.0 eV. 以LOFX作为客体材料, 掺杂在主体材料4,4'-二(9-咔唑)联苯(CBP)中制备了蓝光OLED, 该器件的电致发光(EL)发射峰位于452 nm, 最大亮度为2315 cd·m^-2. 进一步, 选择8-羟基喹啉铝(Alq₃)作为参考材料, 分别以LOFX和Alq₃作为电子传输材料制备了结构相同的单载流子器件和绿色磷光OLED. 在相同的电压下, 以LOFX作为电子传输材料的单载流子器件的电流密度比以Alq₃作为电子传输材料的单载流子器件更高. 同时, 以LOFX作为电子传输材料的绿色磷光OLED获得更高的器件效率. 从这些EL性能可以看出, LOFX同时也是一很好的电子传输材料.     

白光聚合物和聚合物白光器件

有机/聚合物电致发光器件(O/PLEDs)具有低能耗、宽视角、色彩丰富、快速响应、绿色环保以及可制备柔性屏等诸多优异特性,被业界公认为是21世纪最具潜质和最具发展前景的高技术领域之一.白光聚合物电致发光器件(WPLEDs)具有可通过湿法加工技术(如旋涂、丝网印刷、喷墨打印)大大降低器件的制作成本等优点,在显示和照明领域有着极大的应用前景,而受到人们广泛的关注.本文就国内在白光聚合物和聚合物白光器件方面的的研究现状,从聚合物白光器件和制备单一白光聚合物两个方面进行阐述,并介绍这一领域的发展前景和目前亟待解决的一些问题.     

基于激子和电致激基复合物双重发光的白光OLED

基于四苯基乙烯衍生物设计合成了两种蓝光材料TPE-4Br和TPE-3Br,并将其作为有机发光二极管(OLED)器件的发光层,研究发现其可与合适的邻层(空穴传输层/电子传输层)形成电致激基复合物。利用材料的本征激子发光及其电致激基复合物发光,可以得到理想的白光电致发光。将TPE-4Br和TPE-3Br掺杂于mCP中作为发光层,以TAPC和TmPyPB分别作为空穴传输层和电子传输层分别制备器件A和器件B,所得器件在操作电压为9 V时的色坐标分别为(0.32,0.33)和(0.31,0.34)。其中器件B的最大亮度和最大电流效率分别为364.66 cd?m~(-2)与0.79 cd?A~(-1)。     

白光有机电致发光器件中Rubrene超薄层的发光性能

以黄光荧光染料5,6,11,12-Tetraphenylnaphthacene(Rubrene)作为超薄层, 制备了白光有机电致发光器件, 并采用改变荧光超薄层厚度的方法, 通过表征器件的电致发光光谱, 分析了超薄层中染料浓度对器件性能的影响. 研究结果表明, 在荧光染料Rubrene的厚度为0.3 nm时, 器件可以同时实现黄光和蓝光的等强度发射, 从而得到性能优良的白光器件, 最高亮度达到3700 cd/m², 颜色坐标为(0.32, 0.33). 器件中蓝光来自N,N′-Bis-(1-naphthyl)-N,N′- biphenyl-1,1′-biphenyl-4,4′-diamine(NPB)的电致发光, 而器件优良的光电性能是由于Rubrene分子直接载流子陷阱(DCT)效应和NPB分子向Rubrene分子传递能量的协同作用所致.     

Solution-Processed White Circularly Polarized Organic Light-Emitting Diodes Based on Chiral Binaphthyl Emitters

By combining the blue and orange CPL or functionalized bis-benzoxanethones emitters (S-/R- BN-tCz and S-/R- BN-PXZ ), warm white CP-OLEDs were fabricated using solution-processed single emitting layer strategy. The successful realization of white CP-EL benefited from the same stable binaphthyl chirality and similar rigid structure of the two emissive CPL emitters. The devices exhibited the low turn-on voltage of ≈4.3 V, maximum luminance of ≈10200 cd m⁻² and maximum current efficiency of ≈2.0 cd A⁻¹. Most significantly, the devices with CIE coordinates of (0.32, 0.45) displayed intense CP-EL signals in the spectral range of 450 to 650 nm, and showed stable g_EL values of ≈10⁻³ as the luminance increased from 100 to 6000 cd m⁻². To the best of our knowledge, this work provides for the first time a simple and feasible strategy to fabricate solution-processed white CP-OLEDs based on the co-doping of the CPL emitters.     

Aromatic-Imide-Based Thermally Activated Delayed Fluorescence Materials for Highly Efficient Organic Light-Emitting Diodes

Aromatic-imide-based thermally activated delayed fluorescence (TADF) materials with a twisted donor–acceptor–donor skeleton were efficiently synthesized and exhibited excellent thermal stability and high photoluminescence quantum yields. The small ΔE_ST value (<0.1 eV) along with the clear temperature-dependent delayed component of their transient photoluminescence (PL) spectra demonstrated their excellent TADF properties. Moreover, the performance of organic light-emitting diodes in which TADF materials AI-Cz and AI-TBCz were used as dopants were outstanding, with external quantum efficiencies up to 23.2 and 21.1 %, respectively.     

Room-Temperature Multiple Phosphorescence from Functionalized Corannulenes: Temperature Sensing and Afterglow Organic Light-Emitting Diode**

Corannulene-derived materials have been extensively explored in energy storage and solar cells, however, are rarely documented as emitters in light-emitting sensors and organic light-emitting diodes (OLEDs), due to low exciton utilization. Here, we report a family of multi-donor and acceptor (multi-D-A) motifs, TCzPhCor, TDMACPhCor, and TPXZPhCor, using corannulene as the acceptor and carbazole (Cz), 9,10-dihydro-9,10-dimethylacridine (DMAC), and phenoxazine (PXZ) as the donor, respectively. By decorating corannulene with different donors, multiple phosphorescence is realized. Theoretical and photophysical investigations reveal that TCzPhCor shows room-temperature phosphorescence (RTP) from the lowest-lying T₁; however, for TDMACPhCor, dual RTP originating from a higher-lying T₁ (T₁^H) and a lower-lying T₁ (T₁^L) can be observed, while for TPXZPhCor, T₁^H-dominated RTP occurs resulting from a stabilized high-energy T₁ geometry. Benefiting from the high-temperature sensitivity of TPXZPhCor, high color-resolution temperature sensing is achieved. Besides, due to degenerate S₁ and T₁^H states of TPXZPhCor, the first corannulene-based solution-processed afterglow OLEDs is investigated. The afterglow OLED with TPXZPhCor shows a maximum external quantum efficiency (EQE_max) and a luminance (L_max) of 3.3 % and 5167 cd m⁻², respectively, which is one of the most efficient afterglow RTP OLEDs reported to date.     

Achieving Solution-Processed Non-Doped Single-Emitting-Layer White Organic Light-Emitting Diodes through Adjusting Pyrene-Based Polyaromatic Hydrocarbon

Single-emitting-layer white organic light-emitting diodes (SEL-WOLEDs) have developed rapidly in recent years due to the outstanding advantages of high efficiency, simple device structure, low cost, less phase separation, and stable emission color. Nevertheless, the relatively complicated host-dopant system is usually essential for most previous SEL-WOLEDs and the development of simple non-doped SEL-WOLEDs lags behind. Hence the straightforward synthesis of single-white-emitting molecules for non-doped SEL-WOLEDs still remains a great challengeable task. In this article, we designed and synthesized two new pyrene-based polyaromatic hydrocarbons (PAHs) and used them as emitting layer materials in the OLED devices. When the molecules change from the mono-fused one to bis-fused one, the emitting light changes from greenish to white color. Further study indicated that the bis-fused molecule PyD with more twisted and extended backbone packed in neat Cmca space group in single-crystal system compared with P2₁/n for PyS, which may be favorable to form excimers in the solid state and broaden the emission spectrum in the OLEDs. As a result, a solution-processed non-doped single-white-emitting-molecule SEL-WOLED with high performance (e. g., a high color rendering index of 66) is reported. The findings will be beneficial not only to further development of simple WOLEDs, but also to other related organic optoelectronic technology.     

无间隔层结构的高效率荧光/磷光混合型白光有机发光二极管

采用磷光红光/荧光蓝光/磷光绿光无间隔层三发光层结构,制备出了高效率荧光/磷光混合型白光有机发光二极管(OLEDs),其中选取具有高荧光量子产率(PLQY)的荧光染料4P-NPD(双[N-(1-萘基)-N-苯基-氨基]四联苯)作为蓝光发射分子,以及常用的高效磷光染料Ir(MDQ)₂(acac)和Ir(ppy)₃(acac)分别作为红光和绿光的客体,通过混合和掺杂的方法制备了相应的发光层,实现了发光层中激子的有效利用和白光发射。 制备的白光器件最大电流效率和功率效率分别达到了27.1 cd/A和30.3 lm/W,当电压为6 V时,CIE色坐标为(0.33,0.41),显色指数CRI为70,色温CCT为5432 K。 在此基础上,设计制备了高色温的荧光/磷光混合型白光OLEDs,其色温(CCT)达到了7106 K。     

一种热活化延迟荧光黄光材料的合成、性能及高效率电致发光器件

利用吩噁嗪和嘧啶分别作为电子给体和电子受体，通过Buchwald-Hartwig和Suzuki偶联反应成功合成了一种热活化延迟荧光黄光材料pPBPXZ.密度泛函理论计算显示，pPBPXZ分子中吩噁嗪和嘧啶结构单元间的二面角接近90°，而两个嘧啶结构单元与连接二者的苯环间的二面角接近0°；pPBPXZ的最高电子占据轨道主要分布在吩噁嗪结构单元上，最低电子未占轨道主要分布在嘧啶环和苯环上，两种分子轨道只有很小部分重叠.循环伏安、热重和差热测试表明，pPBPXZ具有高的电化学稳定性和热稳定性.在甲苯溶液中，pPBPXZ在360~495 nm显示出了明显的分子内电荷转移跃迁吸收，室温发光峰出现在535 nm.根据低温（77 K）荧光和磷光光谱，计算得到pPBPXZ的最低激发单重态和最低激发三重态能级分别为2.57 eV和2.48 eV，能级差（△E_ST）仅为0.09 eV.利用pPBPXZ作为发光层客体掺杂材料，制备出了高效率的黄光电致发光器件.器件的发射峰出现在552~560 nm，最大电流效率、功率效率和外量子效率分别达到了49.9 cd/A、49.0 lm/W和15.7%，而且发光效率受pPBPXZ掺杂浓度影响较小.     

Highly Efficient Solution-Processed Blue Phosphorescent Organic Light-Emitting Diodes Based on Co-Dopant and Co-Host System

The low-lying HOMO level of the blue emitter and the interfacial miscibility of organic materials result in inferior hole injection, and long exciton lifetime leads to triplet-triplet annihilation (TTA) and triplet-polaron annihilation (TPA), so the efficiencies of blue phosphorescent organic light-emitting diodes (PhOLEDs) are still unsatisfactory. Herein, we design co-host and co-dopant structures to improve the efficiency of blue PhOLEDs by means of solution processing. TcTa acts as hole transport ladder due to its high-lying HOMO level, and bipolar mCPPO1 helps to balance carriers’ distribution and weaken TPA. Besides the efficient FIr6, which acts as the dominant blue dopant, FCNIrPic was introduced as the second dopant, whose higher HOMO level accelerates hole injection and high triplet energy facilitates energy transfer. An interesting phenomenon caused by microcavity effect between anode and cathode was observed. With increasing thickness of ETL, peak position of electroluminescence (EL) spectrum red shifts gradually. Once the thickness of ETL exceeded 140 nm, emission peak blue-shifts went back to its original position. Finally, the maximum current efficiency (CE), power efficiency (PE), and external quantum efficiency (EQE) of blue phosphorescent organic light-emitting diode (PhOLED) went up to 20.47 cd/A, 11.96 lm/W, and 11.62%, respectively.     

导电聚合物有序超薄膜的合成及其作为有机电致发光器件空穴注入层

采用修饰多层LB膜的方法制备了导电聚合物聚-3,4-乙烯二氧噻吩/二十烷酸(PEDOT:AA)复合层状有序膜, 构筑了一种导电聚合物镶嵌的多层有序膜结构. 将这种导电聚合物有序薄膜沉积于ITO电极表面, 将其作为有机电致发光二极管(OLED)的空穴注入层, 并研究了ITO/(PEDOT:AA)/MEH-PPV/Al器件的性能. 研究结果表明, 与采用聚3,4-乙烯二氧噻吩/聚苯乙烯磺酸(PEDOT:PSS)自组装膜和旋涂膜作为空穴注入层的ITO/(PEDOT:PSS)/MEH-PPV/Al器件相比, 器件的发光效率增加, 起亮电压降低. 我们认为这是由于PEDOT:AA薄膜提供了一种有序层状结构后, 减小了ITO与MEH-PPV间的接触势垒, 改善了空穴载流子注入效率. 进一步的研究表明, 由于PEDOT:AA多层膜间靠较弱的亲水、疏水作用结合, 这种导电多层有序膜的热稳定性与普通LB膜相似, 在较高温度下发生从层状有序态到无序态的变化, 这是导致OLED器件性能发生劣化的主要原因.