Browsing by Author "Qiu, Yong"

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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.
Stable and efficient blue fluorescent organic light-emitting diode by blade coating with or without electron-transport layer
(2017-12-01)
Yang, Lan-Sheng
;
Meng, Hsin-Fei
;
Chang, Yu-Fan
;
Lien, Cheng-Hsin
;
Zan, Hsiao-Wen
Multi-layer small-molecule blue fluorescent organic light-emitting diode (OLED) is fabricated by blade coating. The emission layer is based on a mixed host of 1-(7-(9,90-bianthracen-10-yl)-9,9-dioctyl-9H-fluoren- 2-yl) pyrene (PT-404) and electron-transport material 2,7-Bis(diphenylphosphoryl)-9,90 -spirobifluorene (SPPO13), and the blue guest emitter is 4-40-(1E, 10E)-2,20-(naphthalene-2,6-diyl) bis(ethane-2,1diyl) bis(N, N-bis(4-hexyl-Phenyl) aniline) (Blue D). A hole-transport layer of Poly-(9, 9-dioctylfluorenyl2, 7-diyl)-co-(4, 4-(N-(4-sec-butylphenyl)) diphenylamine) (TFB) is added on top of PEDOT: PSS anode. The electrons are blocked away from TFB by a layer of pure host emission layer of PT-404 between TFB and the mixed ehost emission layer. For the devicewith the electron transport layer of Tris(8-hydroxyquinolinato) aluminum (Alq3) blade-coated over the emission layer the efficiency and lifetime at initial brightness of 500 cd m(-2) are 7.5 cd A(-1) and 150 h for Alq3/CsF/Al cathode. When the Alq3/CsF/Al is replaced by simply CsF/Al over the mixed-host emission layer the efficiency and lifetime are 6.4 cd A(-1) and 300 h (2 times longer than that of the Alq3/CsF/Al cathode). The lifetime depends on the electron-hole balance tuned by the mixed-host blending ratio as well as the electron injection from the cathode. This work shows good stability is possible for all-solution-processed blue OLED. (C) 2017 Published by Elsevier B.V.