Browsing by Author "Chung, Ming-Hua"

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Adjusting optical resonance thickness to increase the conversion efficiency of polymer solar cells
(2010-05-01)
Tsai, Yu Sheng
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Lin, Jian-Shian
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Chu, Wei-Ping
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Wang, Po-Hsun
;
Juang, Fuh-Shyang
The derivatives of C(60), [6,6]-phenyl C61-butyric acid methyl ester (PCBM), and 3-hexylthiophene (P3HT) were dissolved in DCB solvent, then spin coated into an active layer for polymer solar cells. The experimental parameters were studied carefully to obtain the optimum power conversion efficiency (PCE). The primary process for generation of photocurrent in an organic photovoltaic device is the generation of bound electron-hole pairs (excitons) by absorption of energy (photons) from the optical electric field. Modeling was based on the assumption that the photocurrent generation process is the result of the creation and diffusion of photogenerated species (excitons), which are dissociated by charge transfer at the active layer. Improve organic optics absorb by insert organic layer (CuPc or C60) at the active layer/Al interface. This research is divided into two components. First part, we use n-type C60 as transmission layer. When an optimum thickness of C(60) is 5 nm, the J(sc) of polymer solar cell can be increased from 7.26 mA/cm(2) to 7.7 mA/cm(2). The V(oc) decrease is because the energy level of C60 LUMO (lowest unoccupied molecular orbital) at 4.5 eV is higher than the 3.7 eV of PCBM. Second part, we use p-type CuPc as transmission layer. When an optimum thickness of CuPc is 3 nm, the short circuit photo-current density (J(sc)) and open circuit voltage (Voc) of polymer solar cell can be increased from 7.26 mA/cm2 to 8.0 mA/cm2 and 0.56-0.58 V, respectively. The reason is the same as C(60). The Voc increase is because the energy level of CuPc LUMO (lowest unoccupied molecular orbital) at 3.1 eV is lower than the 3.7 eV of PCBM. The Jsc increase is because the 3 nm of CuPc leads to a constructive interference happened in the active layer and thus optical absorption increases. In this study we used 3 nm of CuPc at the active layer/Al interface to enhance the short circuit current density, and the efficiency was increased to 2.94%. (C) 2010 Elsevier B. V. All rights reserved.
Comparison of Different Encapsulating Adhesives to Enhance the Efficiencies and Lifetimes of Polymeric Solar Cells
(2009-04-01)
Chung, Ming-Hua
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Chen, Chen-Ming
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Hsieh, Tsung-Eong
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Tang, Rong-Ming
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Tsai, Yu Sheng
Polymeric solar cells (PSCs) with a derivative of C(60) [[6,6]-phenyl C(61)-butyric acid methyl ester (PCBM)], and 3-hexylthiophene (P3HT) as active layers have been fabricated. The PSC devices were also packaged with glass and novel UV glues to improve their lifetimes and power conversion efficiencies (PCEs). After encapsulation with UV glue I, II, and III, the PCEs of PSCs reached 4, 4.82, and 6%, respectively, and their half-lifetimes increased to 16-18, 26-28, and 90 h, respectively, while the PCEs and half-lifetimes of PSCs without encapsulation were 3.76% and 2.5 h, respectively. (C) 2009 The Japan Society of Applied Physics
Easy Process and Performance Improvement for Top-Emission Organic Light-Emitting Diodes by Using UV Glue as the Insulation Layer on Copper Substrate
(2010-07-01)
Tsai, Yu-Sheng
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Wang, Shun-Hsi
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Juang, Fuh-Shyang
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Chang, Shu-Wei
;
Chen, Chuan-hung
A high heat dissipation material (copper, Cu) was employed as the substrate for top emission organic light-emitting diodes (TEOLEDs). The UV glue was spin-coated onto the Cu substrate as the insulation layer to effectively improve Cu surface roughness and reduce process complexity. From the optoelectronic results, the optimized device with the Cu substrate shows the maximum luminance of 14110 cd/m(2) and luminance efficiency of 7.14 cd/A. The surface and junction temperatures are measured to discuss the heat-dissipating effect on device performance. From the results, TEOLED fabricated on a Cu substrate has lower junction (55.34 degrees C) and surface (25.7 degrees C) temperatures, with the lifetime extended seven times. We employed Cu foil as the substrate for flexible TEOLED with maximum luminance of 10310 cd/m(2) and luminance efficiency of 7.3 cd/A obtained.
Electroluminescent properties of color/luminance tunable organic light emitting diodes and their lifetime enhancement with encapsulation
(2008-09-25)
Chen, Chen-Ming
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Chung, Ming-Hua
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Hsieh, Tsung-Eong
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Huang, Bohr-Ran
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Hsieh, Huai-En
In this work, color/luminance tunable organic light emitting diodes (OLEDs) (ITO glass/naphthyl phenyl benzidine (NPB; 80 nm)/4,4'-bis(diphenylvinylenyl)-biphenyl (ADS082BE; 35 nm)/1,3-bis[2-(2,2'-bipyridine-6-yl)-1,3,4-oxadiazo-5-yl]benzene (Bpy-OXD; 20 nm)/tris-[8-hydroxy-quinoline]aluminum (Alq(3); 50 nm)/lithium fluoride (LiF; 3 nm)/aluminum (Al, 80 nm)) with low turn-on voltage (3 V) and high luminance (4850 cd/m(2) at 9 V) have been successfully manufactured. The experimental results reveal that their electroluminescent properties (e.g. hue, luminescent intensity, etc.) can be modulated by the manipulation for the layer thickness of NPB/ADS082BE/Bpy-OXD and the applied voltages. In addition, we have also demonstrated lab-made UV-curable silicone-acrylate encapsulating resin exhibits excellent gas barrier capability so that the half-lifetimes of OLEDs reach 98 h whereas those without encapsulation are only 9 h. (C) 2008 Elsevier B.V. All rights reserved.
Physical properties of syndiotactic polystyrene (sPS)/poly(2,6-dimethyl-1,4-phenylene oxide (PPO) alloys and their feasible estimation for reflective cups of light emitting diodes (LEDs)
(2011-10-20)
Chung, Ming-Hua
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Lin, Jian-Shian
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Hsieh, Tsung-Eong
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Chen, Nien-Po
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Chen, Chen-Ming
In this paper, the effects of antioxidants and processing parameters on the thermal stability and processability of sPS have been investigated. Experimental results indicate that a long processing duration and mechanic shearing force accelerate the thermal oxidation and addition of antioxidants into sPS can effectively improve color contamination and thermal stability. Furthermore, feasible estimation of sPS/PPO alloys for reflective cups of light emitting diodes (LEDs) have also been made, demonstrating that sPS/PPO alloys are potential candidates by the appropriate prescription of impact modifiers, flame retardants, and titanium dioxide. (C) 2011 Elsevier B.V. All rights reserved.
Preparation of organic/inorganic hybrid nanocomposites by ultraviolet irradiation and their packaging applications for organic optoelectronic devices
(2011-08-15)
Chung, Ming-Hua
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Lin, Jian-Shian
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Hsieh, Tsung-Eong
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Chen, Nien-Po
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Juang, Fuh-Shyang
By ultraviolet (UV)-assisted synthetic procedure, we have successfully prepared several UV curable organic/inorganic hybrid nanocomposites with excellent gas barrier capabilities, moderate hardness, and good adhesive strength. The experimental results reveal that the physical properties of nanocomposites depend on their chemical structures. Therefore, introduction of silicone and polyurethane (PU) into the Acrylics backbone dramatically raises the adhesive strength as well as refractive index and lowers the gas penetration. Furthermore, we have also applied lab-made nanocomposite g for the encapsulation of organic optoelectronic devices such as OLEDs, flexible OLEDs, and organic solar cells. With the package of lab-made nanocomposite g, the organic optoelectronic devices effectively resist the entry of moisture and oxygen in the air, extending the lifetimes. (C) 2011 Elsevier B.V. All rights reserved.
Synthesis of poly(4-vinylphenol) (PVPh) and polyhedral oligomeric silsesquioxanes-poly(4-vinylphenol) (POSS-PVPh) with low surface energy and their surface properties
(2011-12-15)
Liao, Chun-Hsiung
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Chien, Fu-Ming
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Chen, Chen-Ming
;
Liu, Lung-Chang
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Chung, Ming-Hua
In this paper, we have synthesized poly(4-vinylphenol) (PVPh) and polyhedral oligomeric silsesquioxanes-poly(4-vinylphenol) (POSS-PVPh) with low surface energies and investigated their surface properties. Experimental results reveal that the surface properties of PVPh and POSS-PVPh can be manipulated with the length of PVPh segment and POSS contents, respectively, resulting in the variation of intermolecular hydrogen bonding interactions. In addition, the surface energies of PVPh after thermal treatment of 180 degrees C for 24 h can be less than 20 mJ m(-2) and those of POSS-PVPh without thermal treatment can be less than 25 mJ m-2 while those of poly(tetrafluoroethylene)(PTFE) are 22 mJ m(-2). (C) 2011 Elsevier B.V. All rights reserved.
Synthesis, thermal characterization, and gas barrier properties of UV curable organic/inorganic hybrid nanocomposites with metal alloys and their application for encapsulation of organic solar cells
(2008-11-01)
Chen, Chen-Ming
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Chung, Ming-Hua
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Hsieh, Tsung-Eong
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Liu, Mark O.
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Lin, Jen-Lien
We have successfully prepared ultraviolet (UV) curable organic/inorganic hybrid nanocomposites with good thermal stability, moderate adhesion strength, and excellent barrier capability. In order to improve the gas blocking properties, the metal alloy (Invar) has been blended with lab-made organic/inorganic hybrid nanocomposites, dramatically not only raising the gas resistance but also reducing the shrinkage after UV curing. Moreover, we have also applied lab-made nanocomposite IV for the encapsulation of organic solar cells. The experimental results reveal that introduction of nanocomposite IV can effectively block the penetration of moisture as well as oxygen in the air into the devices and consequently promote the lifetime of organic solar cells. (C) 2008 Elsevier Ltd. All rights reserved.
Ultraviolet-assisted synthesis of encapsulating adhesives and their application for lifetime improvement of organic light emitting diodes
(2009-07-01)
Chen, Chen-Ming
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Chung, Ming-Hua
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Hsieh, Tsung-Eong
;
Huang, Bohr-Ran
;
Hsieh, Huai-En
The lifetimes of organic light emitting diodes (OLEDs) have been Successfully enhanced with the modulation of LiF thickness mid the utilization of encapsulating adhesives, which have been successfully and synthesized with UV irradiation. Experimental results demonstrate that LiF and lab-made encapsulating adhesives can block the invasion of moisture as well as oxygen in the atmosphere into the OLEDs so that the lifetimes of devices with their encapsulation are 18-folds longer than those without encapsulation. (c) 2008 Elsevier B.V. All rights reserved.