Browsing by Author "Yeh, Han-Cheng"

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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.
Blade-coated sol-gel indium-gallium-zinc-oxide for inverted polymer solar cell
(2016-11-01)
Lee, Yan-Huei
;
Tsai, Pei-Ting
;
Chang, Chia-Ju
;
Meng, Hsin-Fei
;
Horng, Sheng-Fu
The inverted organic solar cell was fabricated by using sol-gel indium-gallium-zinc-oxide (IGZO) as the electron-transport layer. The IGZO precursor solution was deposited by blade coating with simultaneous substrate heating at 120 degrees C from the bottom and hot wind from above. Uniform IGZO film of around 30 nm was formed after annealing at 400 degrees C. Using the blend of low band-gap polymer poly[(4,8-bis-(2-ethylhexyloxy)-benzo(1,2-b: 4,5-b')dithiophene)-2,6-diyl-alt-(4-(2-ethylhexanoyl)-thieno[3,4-b]thiophene-)-2-6-diyl)] (PBDTTT-C-T) and [6,6]-Phenyl C71 butyric acid methyl ester ([70] PCBM) as the active layer for the inverted organic solar cell, an efficiency of 6.2% was achieved with a blade speed of 180 mm/s for the IGZO. The efficiency of the inverted organic solar cells was found to depend on the coating speed of the IGZO films, which was attributed to the change in the concentration of surface OH groups. Compared to organic solar cells of conventional structure using PBDTTT-C-T: [70]PCBM as active layer, the inverted organic solar cells showed significant improvement in thermal stability. In addition, the chemical composition, as well as the work function of the IGZO film at the surface and inside can be tuned by the blade speed, which may find applications in other areas like thin-film transistors. (C) 2016 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).
Continuous blade coating for multi-layer large-area organic light-emitting diode and solar cell
(2011-11-01)
Chen, Chun-Yu
;
Chang, Hao-Wen
;
Chang, Yu-Fan
;
Chang, Bo-Jie
;
Lin, Yuan-Sheng
A continuous roll-to-roll compatible blade-coating method for multi-layers of general organic semiconductors is developed. Dissolution of the underlying film during coating is prevented by simultaneously applying heating from the bottom and gentle hot wind from the top. The solvent is immediately expelled and reflow inhibited. This method succeeds for polymers and small molecules. Uniformity is within 10% for 5 cm by 5 cm area with a mean value of tens of nanometers for both organic light-emitting diode (OLED) and solar cell structure with little material waste. For phosphorescent OLED 25 cd/A is achieved for green, 15 cd/A for orange, and 8 cd/A for blue. For fluorescent OLED 4.3 cd/A is achieved for blue, 9 cd/A for orange, and 6.9 cd/A for white. For OLED with 2 cm by 3 cm active area, the luminance variation is within 10%. Power conversion efficiency of 4.1% is achieved for polymer solar cell, similar to spin coating using the same materials. Very-low-cost and high-throughput fabrication of efficient organic devices is realized by the continuous blade-only method. (C) 2011 American Institute of Physics. [doi:10.1063/1.3636398]
General application of blade coating to small-molecule hosts for organic light-emitting diode
(2014-10-01)
Chang, Hao-Wen
;
Lee, Yi-Ting
;
Tseng, Mei-Rurng
;
Jang, Meng-Hao
;
Yeh, Han-Cheng
Blade coating is applied to multi-layer phosphorescent OLED with five small-molecule hosts for the emission layer, including bis[3,5-di (9H-carbazol-9-yl)phenyl]diphenylsilane (SimCP2), 2,6-bis(3-(9H-carbazol-9-yl)phenyl) pyridine (26DCzPPy), 4,4\',4 \'\'-tris-(N-carbazolyl)-triphenylamine (TCTA), 9,9-bis[4-(3,6-di-tert-butylcarbazol-9-yl)phenyl]fluorene (TBCPF), and 2,7-bis(diphenylphosphoryl)-9,9\'-spirobi[fluorene] (SPPO13). In general, blade coating gives low surface roughness around 0.2 nm without phase separation of the emitter and the host. In the large area of 2 cm by 3 cm the film thickness distribution is within 10% and uniform light-emission is achieved. 1,3-Bis[2-(4-tert-butylphenyl)-1,3,4-oxadiazo-5-yl]benzene (OXD-7) is added to tune the electron transport. Among all the hosts, 26DCzPPy and SimCP2 have by far the best electron hole balance and consequently show the highest efficiency. For SimCP2, the maximal efficiency is 15.8 cd/A for blue and 24.2 cd/A for white emission. The order of efficiencies for the hosts is found to be quite different from the order in vacuum evaporation for the same device structures. (C) 2014 Elsevier B.V. All rights reserved.
Infrared proximity sensor using organic light-emitting diode with quantum dots converter
(2012-11-01)
Chen, En-Chen
;
Yeh, Han-Cheng
;
Chao, Yu-Chiang
;
Meng, Hsin-Fei
;
Zan, Hsiao-Wen
An efficient visible-to-infrared conversion film is made by blending CdTe quantum dots (CdTe QDs) of 12 nm diameter in a polyvinylpyrrolidone 360 (PVP 360) polymer matrix cast by water solution. The solid-state photoluminescence quantum efficiency exceeds 10% with emission peak at 810 nm. Strong 810 emission is obtained by combining the quantum dot film and a green polyfluorene light-emitting diode. Color filter is used to remove residual light below 780 nm to make it entirely invisible. Infrared photo-detector is made by blending poly[5-(5-(2,5-bis(decyloxy)-4-methylphenyl)thiophen-2-yl)-2,3-bis(4-(2-ethylhexyloxy)phenyl)-7-(5-methylthiophen-2-yl)thieno[3,4-b]pyrazine] (PBDOTTP) with band-gap 1.2 eV and (6,6)-phenyl-C61-butyric acid methyl ester (PCBM). The pixel contains one PD surrounded by four PLED on its four sides. The active areas of the five devices are all I cm by 1 cm and they are on the same plane. Infrared proximity sensor with photo-current over 300 nA at 10 cm object distance is achieved by detecting the reflected infrared signal. (C) 2012 Elsevier B.V. All rights reserved.
Polymer Infrared Proximity Sensor Array
(2011-04-01)
Chen, En-Chen
;
Shih, Cheng-Yang
;
Dai, Ming-Zhi
;
Yeh, Han-Cheng
;
Chao, Yu-Chiang
A near-infrared proximity sensor array is achieved by integrating a polymer light-emitting diode and a polymer photodetector (PD). A green emission is converted into deep red peaked at 670 nm by the inorganic phosphor Intematix R670 with quantum efficiency of over 20%. A bandpass filter is used to select a spectral tail of phosphor luminescence with a wavelength above 700 nm. The emissive polymer is green polyfluorene. The infrared PD contains a thick film of a blend of poly(3-hexylthiophene) and (6,6)-phenyl-C61-butyric acid methyl ester up to a thickness of 8 mu m. Position of a moving object at a distance of 10 cm is detected in real time by the array with dynamic images displayed on the computer screen.
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.