Browsing by Author "Chang, Hao-Wen"

Now showing 1 - 5 of 5

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.
Interface and thickness tuning for blade coated small-molecule organic light-emitting diodes with high power efficiency
(2013-09-28)
Chang, Yu-Fan
;
Chiu, Yu-Chian
;
Chang, Hao-Wen
;
Wang, Yi-Siang
;
Shih, Yi-Lun
We developed a general method based on fluorescence microscopy to characterize the interface dissolution in multi-layer organic light-emitting diodes (OLEDs) by blade coating. A sharp bi-layer edge was created before blade coating, with the bottom layer being insoluble and top layer soluble. After blade coating, fluorescence images showed that the edge of the top layer shifted when the layer dissolved completely, whereas the bottom layer's edge remained in place as a positioning mark. The dissolution depth was determined to be 15-20 nm when the emissive-layer host of 2,6-bis (3-(9H-carbazol-9-yl) phenyl) pyridine (26DCzPPy) was coated on the hole-transport layer of N, N'-bis(naphthalen-1-yl)-N, N'-bis(phenyl)-benzidine(NPB), which was consistent with a sudden drop in efficiency of orange OLEDs with layer thickness below 20 nm. Thus, the layer thickness of OLEDs was optimized to stay more than 20 nm for blade coating. For a two-color white OLED with the structure TCTA/26DCzPPy:PO-01-TB:FIrpic/TPBI, efficiency was 24 cd/A and 8.5 lm/W at 1000 cd/m(2). For a three-color white OLED with Os(fptz)(2)(dhpm) added as the emitter, the efficiency was 12.3 cd/A and 3.7 lm/W at 1000 cd/m(2). For a green device with the structure TCTA/26DCzPPy: Ir(mppy)(3)/TPBI, the efficiency was 41.9 cd/A and 23.4 lm/W at 1000 cd/m(2). VC 2013 AIP Publishing LLC.
ITO-free large-area top-emission organic light-emitting diode by blade coating
(2016-02)
Chang, Hao-Wen
;
Meng, Hsin-Fei
;
Horng, Sheng-Fu
;
Zan, Hsiao-Wen
;
物理研究所
Large-area top-emitting organic light-emitting diodes (TEOLEDs) with multi-layer structure are successfully demonstrated using the solution-processable blade coating on ITO-free substrate. The semitransparent cathode of TEOLED is composed of lithium fluoride (LiF), aluminum (Al) and silver (Ag). The composition of 3 nm Al and 10 nm Ag has a transmittance of 56% and a sheet resistance of 11 Omega/square is applied to the green phosphorescence device with an emissive area of 2 cm by 2.5 cm. The maximum current efficiency is 25.2 cd/A with high light-emission uniformity within 10% variation. The large-area TEOLEDs show comparable current efficiency as the small-area devices with an emissive area of 2 mm by 2 mm (having the same device structure) and better efficiency than traditional large-area bottom emitting devices. Cesium fluoride (CsF) and n-doped electron transport layer are applied to improve electron injection. At 6 V, the luminance is raised from 141 cd/m(2) to 502 cd/m(2) and 304 cd/m(2), respectively. In n-doped device, a simple Al/Ag cathode is used without LiF. (C) 2015 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.