Browsing by Author "Wong, Wai-Kwok"

Now showing 1 - 6 of 6

Highly efficient and stable sky blue organic light-emitting devices
(2006-09-18)
Lin, Mei-Fang
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Wang, Lei
;
Wong, Wai-Kwok
;
Cheah, Kwok-Wai
;
Tam, Hoi-Lam
A highly efficient and stable sky blue organic light-emitting device doped with a sky blue dopant BUBD-1 has been fabricated, achieving an electroluminescence efficiency of 13.2 cd/A and 6.1 lm/W at 20 mA/cm(2) and 6.7 V, with Commission Internationale del'Eclairage coordinates of (0.16, 0.30) and a half-decay lifetime of 1815 h at an initial brightness of 2640 cd/m(2). This performance is one of the best blue devices ever reported without using hole blocking layer or any p or n dopant in hole or electron transport layer. (c) 2006 American Institute of Physics.
Highly efficient and stable white light organic light-emitting devices
(2007-08-13)
Lin, Mei-Fang
;
Wang, Lei
;
Wong, Wai-Kwok
;
Cheah, Kok-Wai
;
Tam, Hoi-Lam
A highly efficient two-element white light organic light-emitting device with a sky blue dopant BUBD-1 and a yellow dopant TBRb was fabricated. The device achieved an electroluminescence efficiency of 17.1 cd/A and 7.9 lm/W at 20 mA/cm(2). From 112 to 32 010 nits, the CIEx,y coordinates variation was Delta(x,y)<+/-(0.01,0.01), which is superior to common white light organic light-emitting devices (OLEDs) that tend to change color with drive conditions. Moreover, the device reached a half-decay t(1/2) lifetime over 40 000 h at an initial luminance of 300 cd/m(2). This result is among the best records of fluorescent white light OLEDs. (C) 2007 American Institute of Physics.
Highly efficient white light organic light-emitting device
(2007-01-01)
Lin, Mei-Fang
;
Wang, Lei
;
Wong, Wai-Kwok
;
Cheah, Kok-Wai
;
Tam, Hoi-Lam
A highly efficient white organic light-emitting device (OLED) with a novel sky blue dopant BUBD-1 in a two-color emission system was fabricated. The device achieved an EL efficiency of 17.1 cd/A and 7.9 lm/W at 20 mA/cm 2 with CIEx,y coordinates of (x=0.29, y=0.41) which was not changed with drive conditions. The white light OLED reached a half-decay t(1/2) lifetime over 40,000 hours at an initial luminance of 300 cd/m(2).
Highly efficient white organic light-emitting diodes with single small molecular emitting material
(2007-10-29)
Wang, Lei
;
Lin, Mei-Fang
;
Wong, Wai-Kwok
;
Cheah, Kok-Wai
;
Tam, Hoi-Lam
We demonstrate a highly efficient white organic light emitting device with fluorescent small molecule 4,4'-bis(9-(1-naphthyl)anthracene-10-yl)biphenyl (BUBH-3). With a simple device architecture of indium tin oxide/tris 4,4',4'-tris-N-naphthyl-N-phenylamino-triphenylamine (60 nm)/N,N'-bis-(1-naphthyl)-N,N'-diphenyl-1,1'-biphenyl-4,4'-diamine (10 nm)/BUBH-3 (45 nm)/Alq(3) (15 nm)/LiF (1 nm)/Al (150 nm), a white light with CIEx,y color of (0.31,0.36) was generated. The device achieved one of the best single-emitting-material electroluminescence performance of white organic light-emitting devices with efficiencies of 7.0 cd/A and 3.17 lm/W at 6.9 V. (C) 2007 American Institute of Physics.
Improved OLEDs with single ambipolar material for hole-transport and electron-transport layers
(2008-01-01)
Lin, Mei-Fang
;
Wong, Wai-Kwok
;
Cheah, Kok-Wai
;
Tam, Hoi-Lam
;
Tse, Shing Chi
An organic light-emitting device (OLED) with enhanced efficiency by employing an ambipolar material, 2-methyl-9,10-di(2-naphthyl)anthracene (MADN) as both hole-transport and electron-transport layers has been developed. The efficiency of the device is more than 40% enhanced compared with a control device. Moreover, the operational stability, is also greatly improved as it minimizes the formation of all unstable redox species of Alq(3)(+) as well as NPB-.
Novel host materials for single-component white organic light-emitting diodes based on 9-naphthylanthracene derivatives
(2008)
Wang, Lei
;
Wong, Wai-Yeung
;
Lin, Mei-Fang
;
Wong, Wai-Kwok
;
Cheah, Kok-Wai
A series of 9-naphthylanthracene based dimers and trimers were synthesized and characterized. TGA studies reveal that they are all thermally stable with decomposition temperatures well above 500 degrees C. Upon optical excitation, all of these dimers and trimers show intense blue emission in common organic solvents, accompanied by a new peak at long wavelength in the solid state. They exhibit nanosecond transient lifetimes consisting of two decay components, suggesting the formation of excimers. Single-component light-emitting electroluminescent devices based on these robust materials have been fabricated. The device based on 4,4'-bis(9-(1-naphthyl)anthracen-10-yl)biphenyl exhibits a maximum luminance efficiency of 7.0 cd A(-1) with CIE coordinates of (0.31, 0.36) and luminance of 1396 cd m(-2) at 6.9 V. The device based on 1,3,5-tris(9-(1-naphthyl)anthracen-10-yl)benzene exhibits a maximum luminance efficiency of 5.78 cd A(-1) with CIE coordinates of (0.33, 0.43) and luminance of 1156 cd m(-2) at 7.8 V.