Browsing by Author "Hsieh, Ming-Ta"

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A Near-Zero Cross-Regulation Single-Inductor Bipolar-Output (SIBO) Converter with an Active-Energy-Correlation Control for Driving Cholesteric-LCD
(2011)
Lee, Yu-Huei
;
Fan, Ming-Yan
;
Chen, Wei-Chung
;
Chen, Ke-Horng
;
Liu, Sheng-Fa
A near-zero cross-regulation (near-zero CR) single-inductor bipolar-output (SIBO) converter with an adaptive-energy correlation (AEC) control is proposed as a compact power management solution for driving cholesteric-LCD (Ch-LCD). The SIBO converter can provide a pair of positive and negative output voltages with only one external inductor for achieving the polarity reversion operation in Ch-LCD to obtain high-quality displays. The proposed AEC control decides energy distribution for bipolar outputs without any cross regulation through the embedded prediction function. The chip fabricated in a 0.25 mu m CMOS process demonstrates near-zero cross-regulation at bipolar outputs with 90% peak power conversion efficiency.
Development of stable micro-crystalline silicon AMLCD
(2007-01-01)
Chang, Chan-Ching
;
Chen, Chih-Hsien
;
Peng, Ya-Hui
;
Lee, Yeong-Shyang
;
Hou, Chih-Yuan
Bottom-gate microcrystalline silicon thin film transistors (mu c-Si TFTs) have been produced by the radio frequency glow discharge technique using three different plasma treatment on the interface between microcrystalline and SiN layers. Our first microcrystalline silicon TFTs have better stability at high temperature stress.
Efficient electron injection in organic light-emitting diodes using dipotassium phthalate as n-type dopant
(2008)
Ho, Meng-Huan
;
Hsieh, Ming-Ta
;
Chen, Jenn-Fang
;
Hwang, Shiao-Wen
;
Chen, Chin H.
An efficient n-doped electron transport layer composed of 4,7-diphenyl- 1, 10-phenanthroline (BPhen) and dipotassium phthalate (PAK2) has been developed. By temperature-dependent admittance spectroscopy, the incorporation of PAK2 into BPhen is found to increase electron concentration in BPhen laYer, resulting in raising the Fermi-level to similar to 0.5 eV below its LUMO which further enhances the efficiency of electron injection from Al cathode. When this n-doped layer is adopted in OLED device, the green Alq(3) device can achieve a current efficiency of 3.6 cd/A and a power efficiency of 2.1 lm/W at 20 mA/cm(2) and lower drive voltage of 5.3 V.
Electrical characterization of bathophenanthroline doped with dipotassium phthalate
(2007)
Hsieh, Ming-Ta
;
Chang, Chan-Ching
;
Chen, Jenn-Fang
;
Ho, Meng-Huan
;
Chen, Teng-Ming
Bathophenanthroline (BPhen) doped with dipotassium phthalate (PAK2) was electrically characterized using current-voltage (I-V) and temperature-dependent admittance spectroscopy measurements which demonstrates that the incorporation of PAK2 into BPhen can increase the electron concentration of the BPhen layer resulting in the transformation of the Fermi-level from deep to shallow (around 0.5 eV below LUMO band) and Accordingly, PAK2 is an alternative n-type organic dopant for n-type doping device.
Electrical characterization of organic light-emitting diodes using dipotassium phthalate as n-type dopant
(2008-08-25)
Ho, Meng-Huan
;
Hsieh, Ming-Ta
;
Chen, Teng-Ming
;
Chen, Jenn-Fang
;
Hwang, Shiao-Wen
An efficient n-doped electron transport layer composed of 4,7-diphenyl-1,10-phenanthroline (BPhen) and dipotassium phthalate (PAK2) has been developed. By temperature-dependent admittance spectroscopy, the incorporation of PAK2 into BPhen is found to raise the Fermi level from 1.7 eV to only around 0.5 eV below BPhen's lowest unoccupied molecular orbital, which further enhances the efficiency of electron injection from an A1 cathode. When this n-doped layer is adopted in an organic light-emitting diode device, the green fluorescent 10-(2-benzothiazolyl)-1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H, 5H, 11H-benzo[l]-pyrano[6,7,8-ij]quinolizin-11-one doped device can achieve a current efficiency of 16 cd/A and a power efficiency of 10.9 lm/W at 1000 cd/m(2). (C) 2008 American Institute of Physics.
Electrical Properties of Metal-Silicon Nitride-Hydrogenated Amorphous Silicon Capacitor Elucidated Using Admittance Spectroscopy
(2008-12-01)
Hsieh, Ming-Ta
;
Chen, Jenn-Fang
;
Yen, Kuo-Hsi
;
Zan, Hsiao-Wen
;
Chang, Chan-Ching
Detailed admittance spectroscopy was performed on a metal-silicon nitride-hydrogenated amorphous silicon (MIAS) structure. On the basis of the properties of hydrogenated amorphous silicon (a-Si:H), three simplified equivalent circuit models under various operating conditions (accumulation, depletion and full depletion) are presented along with an alternative direct measurement method at room temperature. Admittance spectroscopy shows that the interface states density between silicon nitride (SiN(x)) and a-Si:H can be determined from the depletion equivalent circuit model. The resisivity and activation energy of a-Si:H can also be obtained using the accumulation and depletion equivalent circuit models. These models can be employed easily to monitor the fabrication parameters of thin-films transistors (TFTs) and to accurately and directly obtain the capacitance model parameters of TFTs. [DOI: 10.1143/JJAP.47.8714]
Highly power efficient organic light-emitting diodes with a p-doping layer
(2006-12-18)
Chang, Chan-Ching
;
Hsieh, Ming-Ta
;
Chen, Jenn-Fang
;
Hwang, Shiao-Wen
;
Chen, Chin H.
In this letter, the authors demonstrate p-i-n organic light-emitting diodes (OLEDs) incorporating a p-doped transport layer which comprises tungsten oxide (WO3) and 4,4('),4(')-tris(N-(2-naphthyl)-N-phenyl-amino)triphenylamine (2-TNATA) to replace the volatile tetrafluro-tetracyanoquinodimethane. The authors propose the 2-TNATA:WO3 composition functions as a p-doping layer which significantly improves hole injection and conductivity of the device that leads to the fabrication of tris(8-quinolinolato)aluminum based p-i-n OLEDs with long lifetime, low driving voltage (3.1 V), and high power efficiency (3.5 lm/W) at 100 cd/m(2). (c) 2006 American Institute of Physics.
Stable and Efficient Organic Light Emitting Diodes Based on a Single Host of p-doped and n-doped Layers
(2009)
Ho, Meng-Huan
;
Hsieh, Ming-Ta
;
Chen, Jenn-Fang
;
Lin, Kuan-Heng
;
Chen, Chin H.
A power-efficient and stable organic light emitting diode with a simplified structure based on 2-methyl-9, 10-di(2-naphthyl)anthracene (MADN) has been developed. The incorporation of 10% tungsten oxide (WO(3)) into MADN and 15% cesium carbonate (Cs2CO(3)) into MADN has been found to improve the hole and electron injection, respectively. Based on this work, it is anticipated that p-i-n OLEDs fabrication process can be considerably simplified and the bill of materials cost can reduced by using one ambipolar host for both the p- and n-doped carrier transport layers.
Study of efficient and stable organic light-emitting diodes with 2-methyl-9,10-di(2-naphthyl)anthracene as hole-transport material by admittance spectroscopy
(2009-01-12)
Ho, Meng-Huan
;
Hsieh, Ming-Ta
;
Lin, Kuan-Heng
;
Chen, Teng-Ming
;
Chen, Jenn-Fang
An organic light-emitting device with enhanced efficiency sby employing 2-methyl-9,10-di(2-naphthyl)anthracene (MADN) as hole-transport material (HTM) has been developed. The admittance spectroscopy studies indicate that using MADN as HTM can reduce the amount of hole carriers injected into the device leading to a well-balanced carrier recombination. The green fluorescent 10-(2-benzothiazolyl)-1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H,11H-benzo[l]pyrano-[6,7,8-ij]quinolizin-11-one doped tris(8-quinolinolato)aluminum device achieved a current efficiency of 21.8 cd/A and a power efficiency of 10.4 lm/W at 20 mA/cm(2) that are 65% higher than those of the control device. The green-doped device also achieved a long half-decay lifetime of 22 000 h at an initial brightness of 500 cd/m(2).
Study of electric characteristics and diffusion effects of 2-methyl-9,10-di(2-naphthyl)anthracene doped with cesium fluoride by admittance spectroscopy
(2010-03-29)
Hsieh, Ming-Ta
;
Ho, Meng-Huan
;
Lin, Kuan-Heng
;
Chen, Jenn-Fang
;
Chen, Teng-Ming
In this work, the admittance spectroscopy studies show that doping cesium fluoride (CsF) into 2-methyl-9,10-di(2-naphthyl)anthracene (MADN) can greatly decrease the resistance of MADN and raises the Fermi level from deep level to only 0.1 eV below the lowest unoccupied molecular orbital, resulting in enhancing the electron injection. In addition, the diffusion width of CsF from doped MADN layer into tris(8-quinolinolato)aluminium is clearly observed by capacitance-frequency measurement and is about 9.4 nm. Moreover, the diffusion width is significant to be affected by external thermal.
Study of electrical characterization of 2-methyl-9, 10-di(2-naphthyl)anthracene doped with tungsten oxide as hole-transport layer
(2009-07-20)
Hsieh, Ming-Ta
;
Ho, Meng-Huan
;
Lin, Kuan-Heng
;
Chen, Jenn-Fang
;
Chen, Teng-Ming
An efficient p-doped transport layer composed of an ambipolar material, 2-methyl-9,10-di(2-naphthyl)anthracene (MADN) and tungsten oxide (WO(3)) has been developed. The admittance spectroscopy studies show that the incorporation of WO(3) into MADN can greatly improve the hole injection and the conductivity of the device. Moreover, when this p-doped layer was incorporated in the tris(8-quinolinolato)aluminum-based device, it achieved a current efficiency of 4.0 cd/A and a power efficiency of 2.4 lm/W at 20 mA/cm(2). This work paves the way to simplify the fabrication of future p-i-n organic light-emitting devices with a single common ambipolar MADN material.
Study of hole concentration of 1,4-bis[N-(1-naphthyl)-N-'-phenylamino]-4,4(') diamine doped with tungsten oxide by admittance spectroscopy
(2006-09-04)
Hsieh, Ming-Ta
;
Chang, Chan-Ching
;
Chen, Jenn-Fang
;
Chen, Chin H.
;
電子物理學系
The effect of tungsten oxide (WO3) incorporation into 1,4-bis[N-(1-naphthyl)-N-'-phenylamino]-4,4(') diamine (NPB) layer is investigated in NPB-tris(8-hydroxyquinoline)aluminium heterojunction organic light-emitting diodes. The admittance spectroscopy studies show that increasing the WO3 volume percentage from 0% to 16% can increase the hole concentration of the NBP layer from 1.97x10(14) to 1.90x10(17) cm(-3) and decrease the activation energy of the resistance of the NPB layer from 0.354 to 0.176 eV. Thus, this incorporation reduces the Ohmic loss and increases the band bending in the NBP layer near the interface, resulting in an improved hole injection via tunneling through a narrow depletion region. (c) 2006 American Institute of Physics.
Study the electrical properties of non-crystalline semiconductor by admittance spectroscopy
(2007)
Hsieh, Ming-Ta
;
Chang, Chan-Ching
;
Chen, Jenn-Fang
;
Zan, Hsiao-Wen
;
Yen, Kuo-Hsi
We developed three types of equivalent circuit model to investigate the electrical properties of non-crystalline semiconductor. From the equivalent circuit models, parameters of non-crystalline semiconductor can be easily obtained by admittance spectroscopy. This method also can be utilized in the optimization of device process as well.
Using tunneling junction to enhance hole-injection in organic light-emitting diodes
(2005)
Chang, Chan-Ching
;
Hwang, Shiao-Wen
;
Hsieh, Ming-Ta
;
Ma, Jia-Wei
;
Chen, Chin H.
We demonstrate enhanced hole-injection and lower driving voltage in vacuum-deposited organic light-emitting diodes (OLEDs) with a novel tunneling junction composed of the Mg:Alq(3)/WO3 layer. The device, ITO/Mg:Alq(3)/WO3/NPB/Alq(3)/LiFAl achieved one of the lowest driving voltages of 5.8 V at 20mA/cm(2) for conventional small molecule OLEDs. We propose the laminated Mg:Alq(3)/WO3/NPB functions as a Fowler Nordheim tunneling junction, which can improve hole-injection. It was found to also prolong device lifetime under dc driving, that is comparable to the best reported for the Alq(3) emitter.