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1、Contents BackgroundExperimental detailResults and discussionConclusionsu 全色显示u 固体照明光源u 液晶显示的背光源WOLED环境友好超薄重量轻高的发光效率磷光材料：磷光材料：100%100%内量子效内量子效应应，寿命，寿命短短减弱了磷光减弱了磷光WOLEDWOLED运行运行稳稳定性定性 结结合合蓝蓝色色荧荧光和光和红红色或黄色磷光色或黄色磷光发发射体的射体的WOLEDWOLED应应运而生。但由于大运而生。但由于大多数常多数常见见的的荧荧光材料的效率低于磷光材料的。因此，基于高效率光材料的效率低于磷光材料的。因此，基于高
2、效率荧荧光的混光的混合合WOLEDWOLED的的发发展是展是实现实现高性能所不可或缺的。高性能所不可或缺的。Experimental detailThe WOLEDs were based on blue fluorescent emitter PT-86 (purchased from LumTech Corporation) and yellow phosphorescent emitter PO-01 doped into blue host (PT-05) (from LumTech Corporation) and 4, 4-N, N-dicarbazole-biphenyl (CB
3、P) hosts, respectively. Prior to device fabrication, Indium Tin Oxide (ITO)-coated glass substrates were carefully cleaned by scrubbing and sonication. All devices were fabricated with conventional process. 4,4,4-tris(3-methylphenylphenylamino)-triphenylamine (m-MTDATA) and 7-diphenyl-1,10-phenanthr
4、oline (Bphen), served as hole injection layer, and hole-blocking layer (HBL)/electron transporting layer, respectively. Tris(phe-nylpyrazole) Iridium (Ir(ppz)3)was served as hole-transporting layer (HTL) and electron-blocking layer (EBL). The thermal deposition rates were 0.1, 0.05 and 0.5 nm/s for
5、organic materials, LiF and Al, respectively. The active area of the devices was 4 mm2.The EL spectra and CIE coordinates of the devices were measured by a PR650 spectroscan spectrometer, and the current density-voltage (J-V)-luminance characteristics were recorded simultaneously by combining the spe
6、ctrometer with Keithley 2400 programmable voltagecurrent source. The color rendering index (CRI) values of the devices were calculated with software SETFOS 3.0 fromFLUXIM AG. All measure- ments were carried out at room temperature under ambient conditions.Results and discussionAn increase in the PT-
7、86 concentration can reduce the hopping distance and subsequently promote the carrier transport in the emission layer (EML), further increasing the current density in the device. In succession, devices based on PT-86 and PO-01 combinations were fabricated by utilizing BPhen and Ir(ppz)3 as interlaye
8、r and fixing PT-86 doping concentration at 5 wt.%.For device D1, a relativelylarger increase in yellow with respect to the blue emission (ratio of the photons from PO-01 and PT-86 emission: RY/B) is found in EL spectra at low voltages ( 6V),while the RY/B is nearly unchanged at higher voltages.Fig.4
9、. 在低驱动电压下，由于Ir(ppz)3电子阻挡层的存在，电子更多的用于发射蓝光，极少的注入电子可以到达中间的Y-EML，形成发黄光的激子。电压的增加使得更多的电子通过EBL，在Y-EML得到高的电子浓度，导致黄光发射增强，RY/B增加。当电压增加到6V时， Y-EML中多余的电子将转移到B-EML中，与此同时，Y-EML利用空穴。因此，在整个EML层中，载流子/激子达到平衡，最终导致高电压下RY/B 稳定。It can be noted that the RY/B initially increases and then decreases dramatically with a furth
10、er increase in applied voltage. The PO-01 exciton recombination region of device C1, as distinct from device D1, is mainly located at the HTL/Y-EML interface, where there is a much higher exciton density at the same applied voltage. Thus, device C1 will show a more severe TTA and TPA at high applied
11、 voltage, which restricts the enhancement of the yellow emission intensity. Therefore, a decrease in RY/B is observed. For device C1, the reason for the increase in RY/B at low voltage is the same with that of device D1. While the decrease in RY/B at higher applied voltage is proved to be the triple
12、ttriplet annihilation (TTA) and triplet-polaron annihilation (TPA) of PO-01 exciton. because PO-01 acts as a transporting channel in CBP (see Fig. 4(c). Fig.4.ConclusionsWe have demonstrated efficient WOLEDs using complementary blue fluorescence and yellow phosphorescence based on different device s
13、tructures. The best white device reaches a maximum CE of 24.7cd/A at 1000 cd/m2 with CIE coordinate of (0.44, 0.48).Devices based on different device architectures exhibit improved color stability. In particular, the CIE coordinate variations of the best device are only (0.01, 0.01) over the luminance range of 103104 cd/m2Thanks For Your Attention ！
