Fabrication Study of Highly-Efficient Deep-Blue Organic Light Emitting Diodes

蘇迪庫馬(KUMAR, SUDHIR)

指導教授 ： 周卓煇

國立清華大學/工學院/材料科學工程學系/博士(2015年)

摘要

Deep blue emission is crucial for achieving high-quality displays and lightings, while high-efficiency is required to enable the corresponding products energy-saving. Wet- and dry-process feasible efficient deep-blue emitter is highly desired to realize, respectively, low cost roll-to-roll fabrication of large area and high performance devices with precise deposition of organic layers. In this study, we demonstrate high efficiency ultra-deep blue and deep-blue organic light-emitting diodes (OLEDs) using cyanofluorene acetylene conjugate based emitters. Their results and discussion will be shown in two parts.
In the first part, we present high-efficiency and ultra-deep blue OLEDs using a cyanofluorene-acetylene conjugate based emitter, 7,7' ((9,9-dibutyl-
9H-fluorene-2,7-diyl)bis(ethyne-2,1-diyl))bis(9,9-dipropyl-9H-fluorene-2 carbo-nitrile) (C3FLA-2). By spin coating, the C3FLA-2 shows maximum external quantum efficiency (EQE) of 6.1%, and at 100 cd m-2 for example,
its color coordinates are (0.156, 0.055) with an EQE of 5.8%, the highest among all reported wet-processed deep-blue devices of fluorescent, phosphorescent, and thermally activated delayed fluorescent types. By vapor
deposition, the device shows maximum EQE of 8.0%, and at 100 cd m-2 color coordinates of (0.156, 0.048) with EQE of 6.5%, the highest among all the dry-processed counterparts. The record high efficiency may be attributed to the emitter having high quantum yield of 86%, low doping concentration
preventing concentration quenching, and a suitable host facilitating an effective host-to-guest energy transfer.
In the second part, we also demonstrate a high efficiency deep-blue OLED using wet-process feasible donor-acceptor-type cyanofluorene acetylene conjugate based emitter, 7-(2-(9,9-dipropyl-9H-fluoren-2-yl)ethynyl)-9,9-dipropyl -9H-fluorene-2-carbonitrile (CFLA-DPA). In the
doped solution-processed OLED device with 4,4’-bis(9H-carbazol-9-yl)biphenyl (CBP) host, the CFLA-DPA shows a maximum efficacy of 5.6 lm W-1, a maximum current efficiency of 5.4 cd A-1, a maximum EQE of 4.4%, and a peak luminance of 4150 cd m-2 with color coordinates of (0.15, 0.11). The resultant power efficiency is highest among all formerly reported solution-processed deep-blue OLED devices. The high efficacy may be attributed to the emitter having bipolar characteristic which may help to
transport the injected carriers and a suitable host facilitating an effective host-to-guest energy transfer.

關鍵字

有機發光二極體 ； 高效率 ； 深藍光 ； 寬波段 ； 氰氟乙炔 ； 溶劑化顯色 ； 高量子效率 ； 主客體能量轉移 ； 熱穩定性

並列摘要

無資料

並列關鍵字

Organic light emitting diode ； high efficiency ； ultra-deep blue ； wide color gamut ； cyanofluorene acetylene ； sovatochromatism ； high quantum yield ； host to guest energy transfer ； thermal stability

參考文獻

1. A. Bernanose, M. Comte, P. Vouaux, J. Chim. Phys. 1953, 50, 64.

2. A. Bernanose, P. Vouaux, J. Chim. Phys. 1953, 50, 261.

3. A. Bernanose, J. Chim. Phys. 1955, 52, 396.

4. A. Bernanose, P. Vouaux, J. Chim. Phys. 1955, 52, 509.

5. H. Kallmann, M. Pope, J. Chim. Phys. 1960, 32, 300.