Browsing by Author "Chao, Teng-Chih"

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All-small-molecule efficient white organic light-emitting diodes by multi-layer blade coating
(2012-05-01)
Yeh, Han-Cheng
;
Meng, Hsin-Fei
;
Lin, Hao-Wu
;
Chao, Teng-Chih
;
Tseng, Mei-Rurng
Blue and white small-molecule organic light-emitting diodes are fabricated by multi-layer blade coating on hot plate at 80 degrees C with hot wind. Uniform multi-layer structures are made without dissolution due to rapid drying. Only small molecules originally developed for vacuum deposition are used. For hole transport layer of, 4',4 ''-tris(carbazol-9-yl)triphenylamine (TCTA), electron transport layer of 2,2',2 ''-(1,3,5-benzinetriyl)-tris(1-phenyl-1-H-benzimidazole) (TBPI), emissive layer host of, 6-bis(3-(9H-carbazol-9-yl)phenyl)pyridine(26DCzPPy), triplet emitters of bis(3,5-difluoro-2-(2-pyridyl)phenyl-(2-carboxypyridyl)iridium(III) (FIrpic), and cathode of LiF/Al, the peak current efficiency for blue emission is 25.1 cd/A (10.8% and 9.3 lm/W). Orange emitter iridium(III) bis (4-(4-t-butylphenyl) thieno[3,2-c] pyridinato-N,C2')acetylacetonate (PO-01-TB) is added to obtain white emission with CIE coordinate of (0.39, 0.46) [1]. The current efficiency is 34.2 cd/A (11.6% and 12 lm/W) at maximum, 32.4 cd/A at 1000 cd/m(2), and 31 cd/A at 10,000 cd/m(2). (C) 2012 Elsevier B.V. All rights reserved.
All-Solution-Processed Red and Orange-Red Organic Light-Emitting Diodes with High-Efficiencies: The Effect of Mixed-Host Emissive Layers and Thermal Annealing Treatment
(2019-09-01)
Chang, Yu-Fan
;
Yang, Lan-Sheng
;
Su, Hsiao-Tso
;
Liao, Si-Yi
;
Niu, Mu-Chun
The instability of the organic light-emitting diodes (OLEDs) during operation can be attributed to the existence of point defects on the organic layers. In this work, the effect of mixed-host emissive layer and the thermal annealing treatment were investigated to eliminate defects and to boost the device performance. The mixed-host system includes 4,4 ',4 ''-tri (9-carbazoyl) triphenylamine (TCTA) and 2,7-bis(diphenylphosphoryl)-9, 9 '-spirobi[fluorene] (SPPO13). The mixed-host emissive layer with thermal annealing treatment showed low roughness and few pinholes, and the devices fabricated from this emissive layer exhibited high efficiencies, high stabilities, and long lifetimes. The red and orange-red OLEDs exhibited efficiencies of 13.9 cd/A and 24.35 cd/A, respectively. The longest half-lifetime (L-0=500 cd/m(2)) of the red and orange-red OLEDs were 158 h and 180 h, respectively. Efforts were made to solve problems in large-area coating and to reduce the number of defects on in organic layer. Large-active-area (active area=3 cmx4 cm) red phosphorescent OLEDs (PhOLEDs) devices were realized with very high current efficiency up to 9 cd/A.
Single-emission-layer white organic light-emitting devices: Chromaticity and colour-rendering consideration
(2014-02-01)
Fan, Chia-Chan
;
Huang, Ming-Hong
;
Lin, Wei-Chieh
;
Lin, Hao-Wu
;
Chi, Yun
The chromaticity and colour-rendering capability of solution-processed single emission layer (EML) white organic light-emitting diodes (W-OLEDs) can be precisely tuned by manipulating the dopant compositions in the EMLs. In this work, we numerically modelled binary, ternary, and quaternary doping single EML W-OLEDs. The correlated colour temperature (CCT), colour-rendering index (CRI), and spectral designs were correlated. The simulation predicted that the quaternary doping system possesses the best chromaticity performance. The corresponding binary, ternary and quaternary doping single EML W-OLEDs were fabricated and characterised to verify the calculation. The solution-processed quaternary doping W-OLEDs were designed with CRI values up to 85, deviations from the Planckian locus (D-u'v') as low as +0.0009, an EQE of 13.7%, a power efficacy of 14.7 lm/W and current efficiency of up to 24.9 cd/A at 1000 cd/m(2). (C) 2013 Elsevier B.V. All rights reserved.
Uniform dispersion of triplet emitters in multi-layer solution-processed organic light-emitting diodes
(2010-12-01)
Huang, Sheng-Yang
;
Meng, Hsin-Fei
;
Huang, Heh-Lung
;
Chao, Teng-Chih
;
Tseng, Mei-Rurng
The influence of the iridium complex solubility on the efficiency of multi-layer solution-processed organic light-emitting diode is demonstrated by synthesized orange triplet iridium complexes with the same core. The solubility of the iridium(III) bis(4-phenylthieno13,2-clpyridinato-N,C(2)') acetylacetonate is increased and uniform dispersion of iridium complex in polymer host poly(vinylcarbazole) is achieved by tert-butyl and n-hexyl group modification. Blade coating technique is utilized to achieve tri-layer structures with a polymer hole-transporting layer poly[(9,9-dioctylfluoreny1-2,7-diyl)-co-(4,4'-(N-(4-s-butylphenyl))diphenylamine)] a host-guest emissive layer, and small-molecule hole-blocking layer 1,3,5-tris(N-phenylbenzimidazol-2-yl) benzene. The efficiency as high as 20 cd/A is achieved for orange-emitting device. (C) 2010 Elsevier B.V. All rights reserved.
Unmodified small-molecule organic light-emitting diodes by blade coating
(2012-10-01)
Chang, Yu-Fan
;
Chiu, Yu-Chian
;
Yeh, Han-Cheng
;
Chang, Hao-Wen
;
Chen, Chun-Yu
Blade coating with substrate heating and hot wind is demonstrated to be a general platform for multi-layer deposition of unmodified small-molecule organic semiconductors. Most unmodified small molecules, originally designed for vacuum evaporation, can be blade coated while the solubility is above 0.5 wt.%. High uniformity is achieved for scale over 5 cm. Orange devices by evaporation and blade coating are compared with 4,4'-bis(carbazol-9-yl)biphenyl (CBP) as the host, iridium(III) bis(4-(4-t-butylphenyl)thieno[3,2-c]pyridinato-N,C-2') acetylacetonate (PO-01-TB) as the emitter. The efficiency difference is within 10%. When 2,6-bis(3-(9H-carbazol-9-yl)phenyl)pyridine (26DCzPPy) is used as the host, the current efficiencies are 40 cd/A for orange, 32 cd/A for green, and 20 cd/A for blue. The optimized organic light-emitting diodes (OLED) structure developed for vacuum deposition can therefore be exactly copied by the low cost blade coating method in solution. (C) 2012 Elsevier B.V. All rights reserved.
Vacuum-free lamination of low work function cathode for efficient solution-processed organic light-emitting diodes
(2012-03-01)
Chang, Yu-Fan
;
Chen, Chun-Yu
;
Luo, Fang-Tsai
;
Chao, Yu-Chiang
;
Meng, Hsin-Fei
The low work function cathode of blade-coated organic light-emitting diode is transferred from a soft polydimethylsiloxane (PDMS) mold by lamination without vacuum. The cathode is a bilayer of polyethylene glycol (PEG) (< 10 nm) and Al (100 nm). A sacrificial layer of polystyrene with low Mw 1500 and melting point of 120 degrees C is inserted between the cathode and PDMS for the subsequent mold removal at 150 degrees C by melting polystyrene. Current efficiency of 3 cd/A (1.1%) and luminance of 2500 cd/m(2) are achieved for green polyfluorene fluorescent emitter. 25 cd/A (8.2%) and 3200 cd/m(2) are achieved for green phosphorescent tris[2-(p-tolyl) pyridine] iridium(III) (Ir(mppy)(3)) emitter in polymer blend host. The efficiency is about 70% of the devices with thermally evaporated cathode. The turn-on voltage is about 5 V higher. (C) 2011 Elsevier B. V. All rights reserved.