High-efficiency conjugated-polymer-hosted blue phosphorescent light-emitting diodes

Highly-efficient blue phosphorescent light-emitting diodes were fabricated based on a conjugated-polymer host by doping bis(2-(4,6-difluorophenyl)-pyridinato-N,C2’) picolinate(FIrpic) into poly(9,9-dioctylfluorene)(PFO).Previously,conjugated polymers were not considered as potential hosts for blue phosphorescent dyes because of their low-lying triplet energy levels.Energy back transfer would occur and lead to poor luminescent efficiency in both photoluminescence(PL) and electroluminescence(EL) processes.However,by inserting a hole-transporting layer of poly(N-vinylcarbazole)(PVK),the energy back transfer was suppressed.At low FIrpic-doping concentrations,PFO emissions were completely quenched;with 8 wt% FIrpic,a maximum luminous efficiency of 11.5 cd/A was achieved.     

新型顶发射有机电致白光二极管的研究

为了提高顶发射白光有机发光二极管(top-emitting white organic light-emitting diodes,TWOLEDs)色谱稳定性,对一种拥有Ag反射镜的新型双蓝光发光单元顶发射器件展开研究,发现结构为Ag/Glass/ITO/MoO₃(5nm)/TAPC(30nm)/TCTA(5nm)/Firpic:TCTA(10%,20nm)/Firpic:TmPyPb(10%,10nm)TPBi(30nm)/LiF(1nm)/Al(0.8nm)/Ag(22nm)/Alq₃(50nm)的蓝光器件具有最佳光电性能,其最高电流效率可以达到9.76cd·A^-1。基于该结构,结合DCJTB荧光染料制备的颜色转换层实现顶发射白光器件。结果表明,当颜色转换层DCJTB浓度为2.5%时,获得了电流效率为2.45cd·A^-1,CIE色坐标为(0.338,0.337)以及显色指数CRI为72的TWOLEDs,器件微腔效应较弱且光谱随电流密度与观测角度改变仅有微弱变化。     

有机反转电致发光器件的负阻特性

对结构为Si/Al/Alqs/PVK:TPD/PTCDA/ITO的有机反转电致发光器件Ⅰ-Ⅴ特性的测量发现,其电压出现了峰值的负阻现象.分析表明:高电压注入时,器件内形成了高浓度的等离子体;载流子寿命和迁移率随注入电压变化;特别是体内出现了严重的电导调制效应使得器件由高阻区变为低阻区,这些是形成负阻特性的主要原因.通过引入双极迁移率和双极扩散系数将空穴和电子的电流连续性方程联合起来,解释了具有负阻区段的Ⅰ-Ⅴ特性曲线.     

White organic light-emitting devices fabricated by spin-coating molecular materials

White organic light-emitting device (WOLEDs) employing molecular mixed host (MH) is demonstrated by spin-coating.The spin-coated film functions as light-emitting layer and hole transporting layer,with the former formed by spin-coating solution containing MH of NPB (N.N'-Bis(naphthalene-1-yl)-N,N'-bis(phenyl)-benzidine) and MADN (2-methyl-9,10-di(2-naphthyl) anthracene),blue dye (4,4'-bis[2-(4-(N,N-diphenylamino)phenyl)vinyl]biphenyl) and yellow dye (5,6,11,12-tetraphenylnaphacene).The performances of the de...     

物理共混制备有机白光电致发光器件

将有机荧光材料NPB,Alq3,DPVBi和Rubrene分别按照一定比例进行物理共混,作为物理混合层,制备了结构为ITO/物理混合层(120 nm)/LiF/Al的有机电致发光器件,研究了物理混合层中不同Rubrene比例对器件性能的影响.结果表明:随着Rubrene共混比例增加,器件色度发生相应改变,并呈现DPVB...     

White organic light-emitting devices using Zn（BTZ）2 doped with Rubrene as emitting layer

Zn(BTZ)2 was synthesized from the complex reaction between zinc acetate dihydrate and 2-(2-hydroxyphenyl) benzothiazolate. Then Zn(BTZ)2 was used as main light-emitting material doped with different amounts of fluorescent dye Rubrene and fabricated a series of white organic light emitting devices. The configurations were as follows: ITO/PVK:TPD/Zn(BTZ)2:Rubrene/Al. The doping concentration of Rubrene in Zn(BTZ)2 was 1.2%, 0.12%, 0.08% and 0.05%, respectively. According to the EL spectra and CIE coordinates of the above devices, the optimum doping concentration (0.05%, weight percent) had been determined. The steady and bright white light emitting of the device with 0.05% doping concentration had been obtained, and the white emission covered a wide range of driving voltage (10--22.5 V). The CIE coordinates were (x=0.341, y=0.334) at the driving voltage of 20 V, which was very close to the equi-energy point (x=0.333, y=0.333), and the corresponding luminance and external quantum efficiency were 4048 Cd/m^2 and 0.63% (4.05 Cd/A), respectively. Lastly, we also discussed the emitting mechanisms of the material and the devices.     

New hybrid encapsulation for flexible organic light-emitting devices on plastic substrates

The hybrid encapsulation for flexible organic light-emitting devices on plastic substrate was investi-gated. The hybrid encapsulation consisted of four periods of AIq3/L.iF layers as the pre-encapsulation layer and a flexible aluminum foil coated with getter as the encapsulation cap. We measured the device lifetime at a continuous constant current of 20 mA/cm2, which corresponded to an initial luminance of 2000 cd/m2. The half-luminance decay time of the encapsulated device was about 458 h. More over, the hybrid encapsulation is ultrathin and flexible, ensuring device bendability.     

Management of singlet and triplet excitons for efficient white organic light-emitting devices

Lighting accounts for approximately 22 per cent of the electricity consumed in buildings in the United States, with 40 per cent of that amount consumed by inefficient (approximately 15 lm W(-1)) incandescent lamps. This has generated increased interest in the use of white electroluminescent organic light-emitting devices, owing to their potential for significantly improved efficiency over incandescent sources combined with low-cost, high-throughput manufacturability. The most impressive characteristics of such devices reported to date have been achieved in all-phosphor-doped devices, which have the potential for 100 per cent internal quantum efficiency: the phosphorescent molecules harness the triplet excitons that constitute three-quarters of the bound electron-hole pairs that form during charge injection, and which (unlike the remaining singlet excitons) would otherwise recombine non-radiatively. Here we introduce a different device concept that exploits a blue fluorescent molecule in exchange for a phosphorescent dopant, in combination with green and red phosphor dopants, to yield high power efficiency and stable colour balance, while maintaining the potential for unity internal quantum efficiency. Two distinct modes of energy transfer within this device serve to channel nearly all of the triplet energy to the phosphorescent dopants, retaining the singlet energy exclusively on the blue fluorescent dopant. Additionally, eliminating the exchange energy loss to the blue fluorophore allows for roughly 20 per cent increased power efficiency compared to a fully phosphorescent device. Our device challenges incandescent sources by exhibiting total external quantum and power efficiencies that peak at 18.7 +/- 0.5 per cent and 37.6 +/- 0.6 lm W(-1), respectively, decreasing to 18.4 +/- 0.5 per cent and 23.8 +/- 0.5 lm W(-1) at a high luminance of 500 cd m(-2).     

单一白色发光层的OLED制备与发光性能研究

研制了两种类型单一白色发光层的有机电致发光器件(OLED),即小分子Zn(BTZ)2的掺杂型器件：ITO／PVK：TPD／Zn(BTZ)2：Rubrene／Al和聚合物LPPP的混合型器件：ITO／混合型发光层／Al,获得了较高的器件亮度和发光效率,且色坐标均非常接近于白色等能点,进而对上述器件的发光和电学性能进行了初步研究。     

LiF用作阴极注入层的有机发光二极管制备

使用真空热蒸发方法,制备了结构为ITO/TPD/Alq3/LiF/Al的有机发光二极管,其中LiF用作阴极注入层,LiF超薄层的加入,增强了电子注入,降低了启亮电压,提高了器件的发光效率和亮度. 实验结果表明:当加入LiF层的厚度为0.5 nm时,器件性能的改善最好,和不含LiF的器件相比,启亮电压由原来的9 V降低到5 V,效率由1.5 cd/A增加到3.3 cd/A,提高了近1倍,然而随着加入LiF层厚度的增加,器件性能的改善效果降低.     

纯有机室温磷光材料研究进展

有机室温磷光（room temperature phosphorescence,RTP）材料凭借制备简单、类型丰富、毒性低等特点,以及在显示、传感、生物成像等方面广阔的应用前景而备受关注．一般的有机RTP材料,其磷光寿命<10 ms,而具有长寿命（τ>100 ms）有机RTP材料其磷光衰减过程裸眼可见,因而具有更广阔的应用前景．本文总结了近年来兼具高效率和长寿命有机RTP材料的分子设计策略,包括引入重原子、形成主-客体材料、构筑H聚集、形成氢键和设计成Donor-Acceptor（D-A）结构．      

有机发光器件的研究进展及应用前景(综述)

介绍了有机电致发光器件OLED（有机发光二极管）发展的历程，论述了有机电致发光材料及其发光原理和器件结构，讨论了该领域的研究热点问题，展望了OLED在新世纪的应用前景。     

Triazolotriazine-based thermally activated delayed fluorescence materials for highly efficient fluorescent organic light-emitting diodes (TSF-OLEDs)

Thermally activated delayed fluorescence (TADF) sensitized fluorescent organic light-emitting diodes (TSF-OLEDs) have shown great potential for the realization ...     

有机电致发光白光器件的研究

白光有机电致发光器件在显示领域有着极大的应用前景,受到人们广泛的关注.通过对白光有机电致发光器件的结构、工作原理、实验的可行性分析、工艺流程、存在的问题等方面进行了分析,对器件结构进行了优化设计,确定了合理的技术路线,提高白光电致发光器件中各成分的发光效率,从而得到了一种较为理想的有机白光电致发光器件.     

Recent progress in ZnO-based heterojunction ultraviolet light-emitting devices

Wide bandgap(3.37 eV)and high excitonbinding energy of ZnO(60 meV)make it a promising candidate for ultraviolet light-emitting diodes(LEDs)and low-threshold lasing diodes(LDs).However,the difficulty in producing stable and reproducible high-quality p-type ZnO has hindered the development of ZnO p–n homojunction LEDs.An alternative strategy for achieving ZnO electroluminescence is to fabricate heterojunction devices by employing other available p-type materials(such as p-GaN)or building new device structures.In this article,we will briefly review the recent progress in ZnO LEDs/LDs based on p–n heterostructures and metal–insulatorsemiconductor heterostructures.Some methods to improve device efficiency are also introduced in detail,including the introduction of Ag localized surface plasmons and single-crystalline nanowires into ZnO LEDs/LDs.     

一种白色有机电致发光器件的发光和电学性能

以铟锡氧化物(ITO)玻璃基片为衬底,8-羟基喹啉锂(Liq)掺杂红荧烯(Rubrene)作为单一发光层,制备结构为ITO/PTV:TPD/Liq:Rubrene/Alq3/Al的白色有机电致发光器件(OLED),对4种不同掺杂浓度器件进行比较,分析了掺杂剂对器件发光亮度的影响,并对上述器件的发光和电学性能进行了研究和探讨.     

Multi-colour organic light-emitting displays by solution processing

Organic light-emitting diodes (OLEDs) show promise for applications as high-quality self-emissive displays for portable devices such as cellular phones and personal organizers. Although monochrome operation is sufficient for some applications, the extension to multi-colour devices--such as RGB (red, green, blue) matrix displays--could greatly enhance their technological impact. Multi-colour OLEDs have been successfully fabricated by vacuum deposition of small electroluminescent molecules, but solution processing of larger molecules (electroluminescent polymers) would result in a cheaper and simpler manufacturing process. However, it has proved difficult to combine the solution processing approach with the high-resolution patterning techniques required to produce a pixelated display. Recent attempts have focused on the modification of standard printing techniques, such as screen printing and ink jetting, but those still have technical drawbacks. Here we report a class of electroluminescent polymers that can be patterned in a way similar to standard photoresist materials--soluble polymers with oxetane sidegroups that can be crosslinked photochemically to produce insoluble polymer networks in desired areas. The resolution of the process is sufficient to fabricate pixelated matrix displays. Consecutive deposition of polymers that are luminescent in each of the three RGB colours yielded a device with efficiencies comparable to state-of-the-art OLEDs and even slightly reduced onset voltages.     

Red organic light emitting device with improved performance using a novel fluorescent dye codoped with phosphor-sensitizer

Efficient red organic light-emitting device consisted of a compound fluorescent-phosphor-sensitized emission layer was fabricated. A novel red fluorescent dye, 3-(dicyanomethylene)-5,5-dimethyl-1-(4-dimethylamino-styryl) cyclohexene (DCDDC), and a green phosphorescent dye, fac tris(2-phenylpyridine) iridium [Ir(ppy)3] were codoped into a host material 4,4’-N,N’-dicarbazolebiphenyl (CBP). By adjusting the component ratio of doping system, a series of devices with different concentration proportion of Ir(ppy)3:DCDDC were constructed. The results demonstrated that the device with 0.2 wt% DCDDC had a maximum power efficiency (η_p) of 2.12 lm/W at a current density of 0.1 mA/cm², which was about 38% higher than that of conventional fluorescent device. When at a current density of 4 mA/cm2 (100 cd/m²) and 52 mA/cm² (1000 cd/m²), the η_p percentage was about 160% and 143% higher than that of conventional device, respectively. A stable red light emission at a peak of 615 nm with Commissions Internationale de l’Eclairage coordinates near the region of (0.56, 0.42) in a wide bias range was also obtained. The improved performances were attributed to the efficient multiple-stage energy transfer from the host to the guest and the suppression of loss mechanism.     

一种多层阳极在电致发光中的应用

报道了一种新型的多层阳极结构在电致发光器件中的应用,其结构为ITO/Ag/ITO,该阳极表面方块电阻为2 Ω/口.制成器件的结构为ITO/Ag/ITO/TPD:PVK/Alq/Al,在同样测试条件下,测得其发光亮度为ITO/TPD:PVK/Alq/Al器件的5倍.另外对器件亮度的衰减作了研究.     

有机发光器件ITO阳极表面能的研究

在测量TIO接触角的基础上，应用调和平均法计算了不同表面处理ITO阳极的表面能和极性度。结果表明：ITO的表面能和极性度随其表面处理方式而变化，并且表面能的变化主要来源于极性分量的增减；经氧等离子体处理后的ITO具有最大的表面能和极性度，这一结果对于优化ITO阳极/有机层界面的性质，改善有机发光器件的性能具有重要意义。