Browsing by Author "Hsu, SF"

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Color-saturated and highly efficient top-emitting organic light-emitting devices
(2005-05-01)
Hsu, SF
;
Lee, CC
;
Hwang, SW
;
Chen, HH
;
Chen, CH
Color-saturated and highly efficient top-emitting organic light-emitting devices (OLEDs) were developed. The device structure studied was glass/reflective silver/indium-tin oxide (ITO; 50, 75, 100, 125 and 150 nm, respectively)/organic electroluminescent (EL) stack/calcium (200 angstrom)/ silver (150 angstrom). By changing the thicknesses of ITO from 50-150 nm in the reflective ITO/Ag anode, different emissive colors from bluish green to orange can be obtained from aluminum tris(8-hydroxyquinoline) (Alq(3)) emitter. By using 2-{2-(t-butyl)-6-[(E)-2-(1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H-pyrido[3,2,1-ij]quinoline-9-yl)-1-ethenyl]-4H-4-pyranliden}malonitrile (DCJTB), 10-(1,3-benzothiazol-2-yl)- 1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H, 11H-pyrano[2,3-f]pyrido[3,2,1-ij]quinoline-11-one (C-545T) and p-bis(p-N,N-diphenyl-aminostyryl)benzene (DSA-ph) as dopants, highly saturated red, green, and blue (RGB) emissions with Commission Internationale de L'Eclairage chromaticity coordinates of (0.64, 0.36), (0.14, 0.75) and (0.14, 0.08) were obtained, respectively. (c) 2004 Elsevier B.V. All rights reserved.
Effects of substrate treatment on the electroluminescence performance of flexible OLEDs
(2004-11-01)
Lee, SN
;
Hsu, SF
;
Hwang, SW
;
Chen, CH
;
友訊交大聯合研發中心
Electroluminescence (EL) performance of flexible organic light-emitting device (FOLED) has been found to be highly dependent upon the morphology of the surface of the indium thin oxide (ITO)/plastic substrate as well as the patterning and processing conditions of the substrate. We will present evidence showing that luminance efficiency of FOLED can be greatly improved by pretreatment. Surface analysis of the ITO/PET by means of atomic force microscope (AFM) and optical microscope will be compared with that of the ITO/glass and the influence of flexible OLEDs substrate treatment by various methods on EL performance will also be discussed. (C) 2004 Elsevier B.V. All rights reserved.
Evaluation on board-level noise filter networks to suppress transient-induced latchup in CMOS ICs under system-level ESD test
(2006-02-01)
Ker, MD
;
Hsu, SF
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
Different types of board-level noise filter networks are evaluated to find their effectiveness for improving the immunity of CMOS ICs against the transient-induced latchup (TLU) under the system-level electrostatic discharge (ESD) test. By choosing proper components in each noise filter network, the TLU immunity of CMOS ICs can be greatly improved. All the experimental evaluations have been verified with the silicon-controlled rectifier (SCR) test structures and the ring oscillator circuit fabricated in a 0.25-mu m CMOS technology. Some board-level solutions can be further integrated into the chip design to effectively improve the TLU immunity of CMOS IC products.
Evaluation on efficient measurement setup for transient-induced latchup with bi-polar trigger
(2005)
Ker, MD
;
Hsu, SF
;
電機學院
;
College of Electrical and Computer Engineering
An efficient measurement setup for transient-induced latchup (TLU) with bi-polar trigger is evaluated in this paper. The influences of the current-blocking diode and the current-limiting resistance on TLU immunity are investigated with the silicon controlled rectifier (SCR) fabricated in a 0.25-mu m CMOS technology. The measurement setup without a current-blocking diode but with a small current-limiting resistance is recommended to evaluate TLU immunity of CMOS ICs. This recommended measurement setup not only can accurately judge the TLU level of CMOS ICs without over estimation, but also is beneficial to avoid electrical over-stress (EOS) damage on device under test (DUT). To further prove the utility of this recommended TLU measurement in the real circuits, a ring oscillator fabricated by 0.25-mu m CMOS technology is used as the test circuit for verification.
Fabrication of blue top-emitting organic light-emitting devices with highly saturated color
(2004-11-01)
Hsu, SF
;
Lee, CC
;
Hu, AT
;
Chen, CH
;
友訊交大聯合研發中心
Blue top-emitting organic light-emitting devices (TOLEDs) with highly saturated color were developed by microcavity effect. The device structure studied was glass/reflective silver/indium-tin oxide (ITO)/organic electroluminescent stack/semi-transparent cathode (calcium/silver). By changing the thicknesses of ITO and organic layers in the microcavity structure device doped with p-bis(p-N,N-di-phenyl-aminostyryl)benzene (DSA-ph), highly saturated color with Commission Internationale de L'Eclairage chromaticity coordinates (CIEx,y) of (0.14, 0.08) was obtained. (C) 2004 Elsevier B.V. All rights reserved.
Highly efficient orange-emitting OLEDs based on phosphorescent platinum(II) complexes
(2005-06-02)
Laskar, IR
;
Hsu, SF
;
Chen, TM
;
應用化學系
;
Department of Applied Chemistry
The syntheses, characterisations, photophysical properties and their applications in organic light emitting devices of a series of 2-phenylbenzothiazolato (bt)/substituted 2-phenylbenzothiazolato (X-bt) platinum(II) based square-planar complexes [(X-bt)Pt(acac); acac = acetylacetonate; X = unsubstituted (1), F (2), OMe (3) and CF3 (4)] are discussed. Reaction of K2PtCl4 with btH/X-btH in glacial acetic acid for a few days results in the dinuclear chloro-bridged Pt(II) complex, (bt/X-bt)Pt(mu-Cl)Pt(bt/X-bt) which is cleaved with acetylacetone to give the corresponding mononuclear (bt/X-bt)Pt(acac) complex. The (MeO-bt)Pt(acac) complex has been characterized by X-ray single crystal structure analysis. The packing diagram shows the Pt-Pt distances and the intermolecular spacings are 3.369 and 3.360 angstrom, respectively, which is consistent with excimer formation. It has also been supported by time-resolved photoluminescence (PL) measurements. The nature of the lowest emitting states are the triplet MLCT as well as triplet pi-pi* states and it has been tuned according to the electronic properties of the substituents. The electroluminescent (EL) devices were fabricated by doping platinum complexes 1 and 2 (the corresponding devices denoted as D-1 and D-2, respectively) into the host CBP (4,4'(N,N'-dicarbazole)biphenyl), in the emitting zone with a doping content of 5%, 7% and 9%. The EL performances for these devices are exceptionally high (14.3 and 16.0 cd A(-1) @2 mA cm(-2) and luminances 10 550 and 11320 cd m(-2) @100mA cm(-2) for D-1 and D-2, respectively). (C) 2005 Elsevier Ltd. All rights reserved.
Highly efficient top-emitting white organic electroluminescent devices
(2005-06-20)
Hsu, SF
;
Lee, CC
;
Hwang, SW
;
Chen, CH
;
應用化學系
We have developed highly efficient white top-emitting organic light-emitting devices with broad emission by modifying both the anode and cathode. To alleviate the undesirable microcavity effect and obtain "broad" white emission, a CFx-coated Ag anode and an index-matching layer (SnO2) capped on a thin Ca/Ag cathode with a maximum transparency of 80% were employed. A top-emitting broad white-light device, based on the dual-layer architecture of light blue and yellow emitters with one of the highest EL efficiencies of 22.2 cd/A (9.6 1m/W) at 20 mA/cm(2) and 7.3 V with Commission Internationale d'Eclairage coordinates of (x = 0.31, y = 0.47), has been demonstrated. (c) 2005 American Institute of Physics.
Investigating photoluminescence and electroluminescence of iridium(III)-based blue-emitting phosphors
(2006-03-27)
Laskar, IR
;
Hsu, SF
;
Chen, TM
;
應用化學系
;
Department of Applied Chemistry
The syntheses of two new cyclometalated ligands [2-(2',4'-difluorophenyl)-4-tert-butylpyridine (F(2)(t)Buppy) and 2-(2',4'-difluorophenyl)-4-oxyhexylpyridine (F(2)HexOppy)] were carried out. Blue-light emitting iridium(III) complex dopants [Ir(F(2)Buppy)(2)(acac/pic)] (acac = acetylacetone; pic = picolinic acid) and [Ir(F(2)HeXOppy)(2)(acac/pic)] were prepared using these cyclometalated ligands with acetylacetone and picolinic acid as their ancillary ligands. The structure of the complexes, [Ir(F(2)(t)Buppy)(2)(acac)] and [Ir(F(2)(t)Buppy)(2)(pic)] were authenticated by X-ray single-crystal structure analysis and showed an octahedral geometry. Comparative absorption and emission spectra of thin-films as well as their solution samples were studied. The variation of the lowest emitting states to their corresponding unsubstituted complexes, [Ir(F(2)ppy)(2)(acac/pic)] was also discussed. The electroluminescent (EL) device was fabricated using [Ir(F(2)(t)Buppy)(2)(pic)] as the dopant (D-I) into the emitting layer and compared with two other EL devices where [Ir(F(2)MeOppy)(2)(acac)] (D-II) and FIrpic (D-III) dopants were used in the same device structure. The lower driving voltages obtained for D-I with respect to D-II and D-III devices were rationalized. The exceptional lowering of the luminance yield of the substituted dopants containing devices, D-I and D-II, to that of D-III which contains the unsubstituted dopant was also investigated. (c) 2005 Elsevier Ltd. All rights reserved.
New dopant and host materials for blue-light-emitting phosphorescent organic electroluminescent devices
(2005-02-10)
Yeh, SJ
;
Wu, MF
;
Chen, CT
;
Song, YH
;
Chi, Y
Efficient organic light-emitting diodes (OLEDs) incorporating Ir-III bis(4,6-difluorophenylpyridinato)3-(trifluoromethyl)-5-(pyridin-2-yl)-1,2,4-triazolate (FIrtaz) and Ir-III bis(4,6-difluorophenylpyridinato)-5- (pyridin-2-yl)-1H-tetrazolate (FIrN4) demonstrate higher-purity blue-light emission than the long-known Ir-III bis(4,6-difluorophenylpyridinato)-picolate (FIrpic) phosphorophore. New host materials with higher glass-transition temperatures were also found to enhance the OLED performance.
Phosphorescence of red Os(fptz)(2)(PPh2Me)(2) doped organic light-emitting devices with n and p hosts
(2006-02-06)
Liu, TH
;
Hsu, SF
;
Ho, MH
;
Liao, CH
;
Wu, YS
We have applied a stericly-hindered red phosphorescent dopant Os(fptz)(2)(PPh2Me)(2) [fptz=3-trifluoromethyl-5-(2-pyridyl)-1,2,4-triazole, PPh2Me=phosphine ligand] in p-type 4,4(')-N,N-'-dicarbazole-biphenyl or n-type bis(2-methyl-8-quinolinolato)(p-phenylphenolato) aluminum host and found that the latter produced higher luminance efficiency at lower doping concentration. We present a model to rationalize this phenomenon in which the n-type host impedes hole transport, which leads to narrower recombination zone near the hole transport layer/emission layer interface than the p-type host, hence, more effective recombination.
Physical mechanism and device simulation on transient-induced latchup in CMOS ICs under system-level ESD test
(2005-08-01)
Ker, MD
;
Hsu, SF
;
電機學院
;
College of Electrical and Computer Engineering
The physical mechanism of transient-induced latchup (TLU) in CMOS ICs under the system-level electrostatic discharge (ESD) test is clearly characterized by device simulation and experimental verification in time domain. For TLU characterization, an underdamped sinusoidal voltage stimulus has been clarified as the realistic TLU-triggering stimulus under the system-level ESD test. The specific "sweep-back" current caused by the minority carriers stored within the parasitic pnpn structure of CMOS ICs has been qualitatively proved to be the major cause of TLU. All the simulation results on TLU have been practically verified in silicon with test chips fabricated by 0.25-mu m CMOS technology.
Syntheses, photoluminescence and electroluminescence of some new blue-emitting phosphorescent iridium(III)-based materials
(2005-01-27)
Laskar, IR
;
Hsu, SF
;
Chen, TM
;
應用化學系
;
Department of Applied Chemistry
The cyclometallated ligand 2-(4',6-difluorophenyl)-4-methoxypyridine (F(2)MeOppyH), whose complexes with iridium(III) emit bright blue to green light, was synthesized in five separate steps. Ir(F(2)MeOppy)(2)(acac), (acacH = 2,4-pentanedione), Ir(F(2)MeOppy)(2)(pic) (picH = 2-picolinic acid), fac-Ir(F(2)MeOppy)(3) and mer-lr(F(2)MeOppy)(3) complexes were synthesized from solution and fully characterized. The structures of Ir(F(2)MeOppy)(2)(acac) and fac-Ir(F(2)MeOppy)(3) were authenticated by X-ray single crystal structure analysis. fec-Ir(F(2)MeOppy)(3) showed a much higher solution photoluminescence (PL) quantum efficiency and blue-shifted emission compared to its counter mer-isomer. All of the complexes showed reversible oxidations between 0.3 and 0.7 V versus the ferrocene/ferrocenium ion. The relative thermodynamic stability of the mer versus fac isomer was investigated and correlated to their corresponding redox and PL properties. Two electroluminescent (EL) devices (D-1 and D-2) were fabricated using the same blue Ir(F(2)MeOppy)(2)(acac) complex as a a dopant but with two different hole blockers, BCP and BAlq, and consequently BCP proved itself a good hole blocker for this type of system. The fabrication of another EL device (D-3) was carried out by using the same dopant, only replacing the host CBP by a wider band gap host, mCP which showed improved luminance, luminance yield and power efficiency (D-2: 133 cd m(-2) 0.66 cd A(-1), 0.22 lm W-1; D-3: 326 cd m(-2); 1.63 cd A(-1); 0.26 lm W-1). (C) 2004 Elsevier Ltd. All rights reserved.
Transient-induced latchup in CMOS technology: Physical mechanism and device simulation
(2004)
Ker, MD
;
Hsu, SF
;
電機學院
;
College of Electrical and Computer Engineering
The physical mechanism of (t) under bar ransient-induced (l) under bar atch (u) under barp (TLU) in CMOS ICs has been clearly characterized by device simulation and experimental verification in time domain perspective. An underdamped sine-wave-like voltage has been clarified as the real TLU-triggering stimulus under system-level (e) under bar lectro (s) under bar tatic (d) under bar ischarge (ESD) test. The specific "sweep-back" current caused by the minority carriers stored within the pnpn structure of CMOS ICs has been qualitatively proved to be the major cause of TLU.