Browsing by Author "Wen, SW"

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4-(Dicyanomethylene)-2-t-butyl-6-(1,1,7,7-tetramethyljulolidyl-9-enyl)-4H-pyran doped red emitters in organic light-emitting devices
(2003-09-22)
Liu, TH
;
Iou, CY
;
Wen, SW
;
Chen, CH
;
應用化學系
We have studied the device optimization of red 4-(Dicyanomethylene)-2-t-butyl-6-(1,1,7,7-tetramethyljulolidyl-9-enyl)-4H-pyran (DCJTB) dye doped Alq(3) emitters in organic light-emitting devices (OLED). By varying the hole injection materials, thickness of hole-transport layer and by evaporation with rubrene as co-dopant, efficiencies of 3.24 cd/A and near saturated CIE color coordinates of x = 0.643, y = 0.354 was achieved without needing additional doping of hole-trap with NPB. From experiments with film thickness variation, it is concluded that the improved electrofluorescent (EL) performance and color saturation are due to the synergistic effects of microcavity, device structural optimization as well as optimal doping of DCJTB with rubrene. We believe this luminance efficiency for red is by far one of the best ever reported for dye-doped electrofluorescent OLEDs. (C) 2003 Elsevier B.V. All rights reserved.
Doped RGB organic electroluminescent devices based on a bipolar host material
(2003)
Wen, SW
;
Yen, CK
;
Liu, TH
;
Chen, CH
;
應用化學系
Development of RGB doped emitters based on the bipolar host of wide bandgap material, 9,10-bis(2-naphthyl)anthracene (ADN) is described. While the blue and green fluorescent dopants of TBP and C-545T achieved EL efficiencies of 5.1 and 11.2 cd/A, respectively in ADN, the red fluorescent DCJTB dopant needed to be doped in a co-hosted mixture of ADN. Alq(3) (60:40) in order to achieve a high efficiency of 4.8 cd/A with a near saturated CIEx,y = 0.64, 0.35 at 2% doping. Luminance efficiencies of all three RGB doped emitters in the bipolar ADN based host are not effected by increased drive current density, thus solving the current-induced fluorescence quenching problem often encountered in organic EL devices.
Experimental and theoretical demonstration on the transport properties of fused ring host materials for organic light-emitting diodes
(2006-01-01)
Tse, SC
;
So, SK
;
Yeung, MY
;
Lo, CF
;
Wen, SW
The charge transport properties of three tertiary-butyl (t-Bu) substituted anthracene derivatives (ADN), critical blue host materials for organic light-emitting diodes (OLEDs), have been investigated experimentally and computationally. From time-of-flight (TOF) measurements, all ADN compounds exhibit ambipolar characters. The hole and electron mobilities are in the range (1-5) x 10(-7) cm(2) V-1 s(-1) Under ail external applied field of about 1 MV cm(-1). Un-substituted ADN has the highest carrier mobilities while heavily t-Bu substituted ADN has the least. The electron and hole conducting properties of are consistent with ab initio calculation, which indicates that the frontier orbitals are localized mainly on the anthracene moiety. t-Bu substitutions in ADN increase the hopping path lengths among the molecules and hence reduce the electron and hole mobilities. The results demonstrate that t-Bu substitution is an effective means of engineering the conductivity of organic charge transporter for OLED applications.
Synthetic study of tetramethyljulolidine - a key intermediate toward the synthesis of the red dopant DCJTB for OLED applications
(2003-01-01)
Balaganesan, B
;
Wen, SW
;
Chen, CH
;
應用化學系
;
友訊交大聯合研發中心
The formation and characterization of a novel chiral sulfonic acid derivative obtained during the synthesis of 1,1,7,7-tetramethyljulolidine (TMJ), a key intermediate towards the red dopant 4-(dicyanomethylene)-2-t-butyl-6-(1,1,7,7-tetramethyljutolidyl-9-enyl)-4H-pyran (DCJTB) used for organic electroluminescent devices, upon bis-annulation of NN-bis(4-methyl-2-butenyl)aniline is described. (C) 2002 Elsevier Science Ltd. All rights reserved.
The role of charge-transfer integral in determining and engineering the carrier mobilities of 9,10-di(2-naphthyl)anthracene compounds
(2006-05-10)
Tse, SC
;
So, SK
;
Yeung, MY
;
Lo, CF
;
Wen, SW
The charge transporting properties of t-butylated 9,10-di(2-naphthyl)anthracene (ADN) compounds have been investigated experimentally and computationally in relation to their molecular structures. The ADN compounds are found to be ambipolar with both electron and hole mobilities in the range of 1-4 x 10(-7) cm(2) V-1 s(-1) (electric field 0.5-0.8 MV/cm). As the degree of t-butylation increases, the carrier mobility decreases progressively. The mobility reduction was examined by Marcus theory of reorganization energies. All ADN compounds possess similar reorganization energies of similar to 0.3 eV. The reduction of carrier mobilities with increasing t-butylation can be attributed to a decrease in the charge-transfer integral or the wavefunction overlap. (c) 2006 Elsevier B.V. All rights reserved.