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Pang H.,Hebei Engineering and Technology Center for Material | Cao J.-H.,Hebei Engineering and Technology Center for Material | Sui Y.,Hebei Engineering and Technology Center for Material | Li Y.-M.,Hebei Engineering and Technology Center for Material | And 2 more authors.
Faguang Xuebao/Chinese Journal of Luminescence | Year: 2013

Polyfluorene containing thiadiazole (PDOF-TAF) was synthesized by palladium-catalyzed Suzuki cross coupling reaction of 2, 7-dibromo-9, 9-dioctyl-9H- fluorene (Br-DOF), 9, 9-dioctyl-9H-fluorene-2, 7-diyldiboronic acid (B-DOF) and 4- (8-(2, 7-dibromo-9-octyl-9H-fluoren-9-yl)octyloxy) -N-(4-(7-(4-(diphenylamino) phenyl)benzo[c][1, 2, 5]thiadiazol-4-yl)phenyl)-N-phenylaniline (Br-TAF). The synthesized polymer was applied as white light-emitting polymer and was used as the emitting layer to prepare the non-doped white organic light-emitting diodes (WOLED) by spin-coating. The color coordinates locate at (0.23, 0.18). By inserting 1, 3, 5-tris(1-phenyl-1H-benzimidazol-2-yl)benzene (TPBI) as electron transport layer and Poly(N-vinylcarbazole) (PVK) as hole transport layer, the emission spectra of the diode cover 410~700 nm visible region, and the color coordinates shift to (0.24, 0.32), locating close to the white point. In addition, the luminescence and current efficiency can reach up to 2020 cd/m2 and 1.4 cd/A, respectively, indicating that the synthesized polymer has highly potential application as the material of white light-emitting layer in WOLED.


Guo J.,Hebei Engineering and Technology Center for Material | Li Z.-Q.,Hebei Engineering and Technology Center for Material | Hua R.-M.,Hebei Engineering and Technology Center for Material | Hua R.-M.,Tsinghua University
Chinese Journal of Liquid Crystals and Displays | Year: 2016

In order to improve the view angle of twisted nematic liquid crystal display (TN LCD), we synthesized a triphenylene discotic liquid crystals and prepared simple optical compensation film by using this material. This triphenylene discotic compound was synthesized from 4-chlorobutyl acetate,methyl 4-hydroxybenzoate and 1,2-dimethoxybenzene by seven steps in high yield. The construction was confirmed by nuclear magnetic resonance (NMR) and elemental analysis (EA). We also measured the parameters and the performances of this compound by polarizing optical microscope (POM), pretilt angle tester and differential scanning calorimetry (DSC). Simple optical compensation film was prepared by several steps including substrate surface treatment, rubbing-alignment, coating and so on. This triphenylene discotic compound has negative optical anisotropy (Δn=-0.0608), wide nematic phase range (54.6~166.4℃), the optical compensation film has a certain compensative effect (Rth=137 nm). This triphenylene discotic compound can be used in optical compensation film of the TN LCD. The preparation method is of simple operation and low cost, which can also realize industrialization easily. © 2016, Science Press. All rights reserved.


Pang H.,Hebei Engineering and Technology Center for Material | Zheng C.-W.,Hebei Engineering and Technology Center for Material | Cao J.-H.,Hebei Engineering and Technology Center for Material | Zhang X.,Hebei Engineering and Technology Center for Material | And 2 more authors.
Chinese Journal of Liquid Crystals and Displays | Year: 2015

In order to realize the fabrication of the OLEDs by solution-processing, synthesis and application of highly soluble organic electroluminescent materials is one of the important ways. In the present work, a ligand containing a structural moiety of 4'-n-propyl-(1,1'-bicyclohexyl)-4-difluorophenyl commonly used in liquid crystal molecules and its iridium complex, Ir(cfpp)2(acac) (cfpp=2-[2,3-difluoro-5-(trans, trans-4"-n-propyl-(1",1'-bicyclohexyl)-4'-yl)phenylpyridine); acac=acetylacetonate) were synthesized. The synthesized iridium complex was used as a green light-emitting dopant material with 2%, 4% and 8% doping concentration (mass fraction) in emissive layer to fabricate OLED devices by spin-coating method, and the structure of OLED device comprises of ITO/PEDOT:PSS/PVK:PBD:Ir(cfpp)2(acac)/TPBi/LiF/Al. When the doping concentration was 8%, the maximum emission wavelength of OLED device appears at 524 nm with the maximum brightness of 3500 cd/m2. When the current density is 20 mA/cm2, the maximum current efficiency and power efficiency of the device are 2.0 cd/A and 0.6 lm/W, respectively, indicating that the prepared device shows the interesting characteristics of electroluminescence. The obtained results imply that it is a practical concept to design and synthesize the soluble organic electroluminescent materials for spin-coating procedure by introduction of the structural moiety of liquid crystal molecules. © 2015, Science Press. All rights reserved.


Lv W.-H.,Shijiazhuang Chengzhi Yonghua Display Material Co.Ltd. | Lv W.-H.,Hebei Engineering and Technology Center for Material | Lv W.-H.,Tsinghua University | Meng J.-S.,Shijiazhuang Chengzhi Yonghua Display Material Co.Ltd. | And 11 more authors.
Chinese Journal of Liquid Crystals and Displays | Year: 2016

In order to meet the different demands of the LCD, six novel polyflurinated dielectric anisotropy liquid crystalline compounds were synthesized. These compounds were synthesized from 2,3-difluoro-propylbenzene or 2,3-difluoro-1-ethoxybenzene by several steps. Their constructions were confirmed by NMR,elemental analysis and GC-MS. The parameters and the performances of these products were measured by DSC, Abbe refractometer and capacitance inductance tester. These polyfluorinated compounds have large optical anisotropy(Δn=0.22~0.33)and large negative dielectric anisotropy(Δε=-7.63~-12.02). These compounds can be used in the LCD matrix to improve partial performance of the LCD. The preparation method is of simple operation and low cost (totle yield: 50%), which can also realize industrialization easily. © 2015, Science Press. All rights reserved.


Wang Y.-Q.,Shijiazhuang Chengzhi Yonghua Display Material Co. | Wang Y.-Q.,Hebei Engineering and Technology Center for Material | Gui L.-H.,Shijiazhuang Chengzhi Yonghua Display Material Co. | Gui L.-H.,Hebei Engineering and Technology Center for Material | And 8 more authors.
Chinese Journal of Liquid Crystals and Displays | Year: 2015

The high birefringence liquid crystals have important applications in LCD, but they are instable under UV exposure due to the conjugated unsaturated structures. The ultraviolet stability of high birefringence liquid crystals was studied in this paper. First, several different additives were added to the liquid crystal mixture A, such as triphenylphosphine oxide,4'-propylbi(cyclohexane)-4-formaldehyde, 4-propyl-4'-cyclopentyl-3,5-difluorobiphenyl and UV-P. The liquid crystal mixtures were poured into TN-7.0-R test cells after stirred uniformly, then the test cells were exposed to ultraviolet, finally the liquid crystal parameters were tested. The results show that the UV stability of liquid crystal A can be significantly improved by UV-P,because the UV absorption of UV-P is most similar with liquid crystal A. © 2015, Science Press. All rights reserved.


Wang M.-X.,Shijiazhuang Chengzhi Yonghua Display Material Co Ltd | Wang M.-X.,Hebei Engineering and Technology Center for material | Gui L.-H.,Shijiazhuang Chengzhi Yonghua Display Material Co Ltd | Gui L.-H.,Hebei Engineering and Technology Center for material | And 12 more authors.
Chinese Journal of Liquid Crystals and Displays | Year: 2015

The UV stability of liquid crystal compounds containing tolane group was studied.It showed that the threshold voltage and birefringence of the liquid crystal decreased after 200 minutes of UV exposure. And it indicated that UV degradation of the liquid crystal depended on not only the absorption wavelength but also the detailed molecular constituents.The UV stability of liquid crystal with different terminal groups and linking groups were analyzed.The measured data showed that the diphenyl acetylene compounds with NCS terminal group exhibited a better UV stability than those with CN terminal group.The compounds with 1,4-cyclohexyl linking group were better than those with-COO-linking group or with none linking group. © 2015, Science Press. All rights reserved.

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