Browsing by Author "Horng, Sheng-Fu"

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13% Efficiency Hybrid Organic/Silicon-Nanowire Heterojunction Solar Cell via Interface Engineering
(2013-12-01)
Yu, Peichen
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Tsai, Chia-Ying
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Chang, Jan-Kai
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Lai, Chih-Chung
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Chen, Po-Han
Interface carrier recombination currently hinders the performance of hybrid organic silicon heterojunction solar cells for high-efficiency low-cost photovoltaics. Here, we introduce an intermediate 1,1-bis[(di-4-tolylamino)phenyl]cyclohexane (TAP() layer into hybrid heterojunction solar cells based on silicon nanowires (SINWs) and conjugate polymer poly(3,4-ethylenedioxy-thiophene):poly(styrenesulfonate) (PEDOT:PSS). The highest power conversion efficiency reaches a record 13.01%, which is largely ascribed to the modified organic surface morphology and suppressed saturation current that boost the open-circuit voltage and fill factor. We show that the insertion of TAP( increases the minority carrier lifetime because of an energy offset at the heterojunction interface. Furthermore, X-ray photoemission spectroscopy reveals that TAP( can effectively block the strong oxidation reaction occurring between PEDOT:PSS and silicon, which improves the device characteristics and assurances for reliability. These learnings point toward future directions for versatile interface engineering techniques for the attainment of highly efficient hybrid photovoltaics.
A 0.05 V driven ammonia gas sensor based on an organic diode with a top porous layered electrode and an air-stable sensing film
(2019-06-07)
Madhaiyan, Govindasamy
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Chen, Chao-Hsuan
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Wu, Yi-Chu
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Horng, Sheng-Fu
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Zan, Hsiao-Wen
In this work, we successfully demonstrated an extremely-low-voltage (0.05 V) gas sensor based on a vertical organic diode with work-function-matched electrodes. With the designed electrodes (MoO3/Al vs. Al), the built-in field in the vertical diode is greatly reduced and hence the diode can be turned on at a very low voltage. By producing nanometer pores in the top electrode, the diode becomes a very sensitive gas sensor to detect ammonia in parts-per-billion (ppb) concentrations. Upon reducing the voltage from 5 V to 0.05 V, this sensor device shows an over 5-times enhancement in the sensitivity. The air-stable sensing film also exhibits a lifetime of 30 days in air. Finally, by connecting with an organic photovoltaic (OPV) device, the gas sensor can be directly powered and switched on by irradiating light on the OPV.
A solvent-free lift-off method for realizing vertical organic transistors with low leakage current and high ON/OFF ratio
(2016-04)
Fang, Xiang
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Lin, Chia-Ho
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Sun, Yung-Tai
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Chin, Huei-Tzu
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Zan, Hsiao-Wen
A solvent-free lift-off method has been introduced to fabricate the aluminum nano-hole array with diameter down to 80 nm as the base electrode for a vertical organic transistor. The imprinted vertical organic transistor exhibited base leakage current density as low as 5 x 10(-5) mA/cm(2) and high ON/OFF current ratio as high as 10(5). (C) 2016 Elsevier B.V. All rights reserved.
Accurate real-time sensing tip for aqueous NO with optical fibers embedded in active hydrogel waveguide
(2018-02-01)
Chung, Chieh-Wen
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Tsai, May-Jywan
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Lin, Peng-Wei
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Huang, Ding-Wen
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Wang, Kuan-Hsun
A NO sensing tip is made by inserting two parallel optical fibers inside a poly 2-hydroxyethyl methacrylate (PolyHEMA) hydrogel waveguide mixed with the probe molecule 1, 2-Diaminoanthraquinone (DAQ). There is a length difference of 1 mm between the two fibers, and the light has to propagate through the difference from the short fiber to the long fiber. The total cross section area of the active hydrogel waveguide embedded with the fibers is only 3mm x 1.2 mm. For practical use the tip is housed in a needle for mechanical protection and the sensing tip is able to detect aqueous NO concentration around 1 mu M with time resolution about 5 minutes. Such a sensing tip can be used to monitor the medical conditions inside the brain after a stroke or a brain injury. (C) 2018 Author(s).
All-solution-processed blue small molecular organic light-emitting diodes with multilayer device structure
(2009-12-01)
You, Jia-Da
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Tseng, Shin-Rong
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Meng, Hsin-Fei
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Yen, Feng-Wen
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Lin, I-Feng
All-solution-processed multilayer blue small molecular organic light-emitting diodes are fabricated by blade coating method. Fluorescent blue host, 1-(7 -(9.9'-bianthracen-10-yl)-9,9-dioctyl-9H-fluoren-2-yl)pyrene, and blue dopant, 4,4'-(1E,1'E)-2,2'-(naphthalene-2,6-diyl)bis(ethene-2,1-diyl)bis(N,N-bis(4-hexylphenyl)aniline),are used to achieve good solubility and pinhole-free thin film by solution process. The multilayer device structure with hole/electron transport layer is achieved by blade coating method without the dissolution problem between layers. The efficiency of the all-solution-processed device is 4.8 cd/A at 1200 cd/m(2), close to that by thermal deposition in high vacuum chamber. The device performance is optimized with the annealing temperature of TPBi layer at 50 degrees C. (C) 2009 Elsevier B.V. All rights reserved.
All-Solution-Processed Multilayered Small-Molecule OLEDs with High Device Efficiency
(2009)
Tseng, Hsin-Rong
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Meng, Hsin-Fei
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You, Jia-Da
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Horng, Sheng-Fu
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Yen, Feng-Wen
All-solution-processed multilayer blue small molecular organic light-emitting diodes are fabri-cated by blade coating method. Fluorescent blue host,1-(7-(9,9'-bianthracen-10-yl)- 9,9-dioctyl-9H-fluoren-2-yl)pyrene, and blue dopant, 4,4'-(IE,I'E)-2,2'(naphthalene-2,6-diyl)bis(ethene-2,1-diyl)bis(N,N-bis(4-hexylphenyl)aniline), are synthesized to achieve good solubility and pinhole free thin film by solution process. The multilayer device structure with holelelectron transport layer is achieved by blade coating method without the dissolution problem between layers. The efficiency of the all-solution-processed device is 4.8 cd/A at 1,200 cd/m(2), close to that by thermal deposition in high vacuum chamber.
Apparatus and method for forming multilayer polymer thin film
(2010-01-28)
Meng, Hsin-Fei
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Horng, Sheng-Fu
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Tseng, Hsin-Rong
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Tuan, Chi-Shen
Apparatus and method for forming multilayer polymer thin film. The method uses a solution container with a gap to prevent the huge amount of solution from directly falling on the first layer. Then the wet film is formed by moving the container with the thin film thickness is decided by the distance between the gap and the substrate. The wet film is dried in a very short time by the heater therefore there is no time for the second solvent to dissolve the first layer. The method can effectively achieve the large-area and multilayer structure in organic devices through solution processing.
Blade coating of Tris(8-hydroxyquinolinato)aluminum as the electron-transport layer for all-solution blue fluorescent organic light-emitting diodes
(2016-02-01)
Chang, Yu-Fan
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Meng, Hsin-Fei
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Fan, Gang-Lun
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Wong, Ken-Tsung
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Zan, Hsiao-Wen
Organic light-emitting diodes (OLEDs) with a low driving voltage and efficient blue fluorescence were fabricated through blade coating. Tris(8-hydroxyquinolinato)aluminum (Alq(3)) is a relatively stable electron-transporting material commonly used in evaporation. However, depositing Alq(3) through a solution process is difficult because of its extremely low solubility organic solvents, a result of its symmetrical molecular structure. In this study, Alq(3) was successfully deposited through blade coating at a very low concentration below 0.1wt%. The OLEDs contained co-dopants BUBD-1 and p-bis(p-N,N-diphenyl-aminostyryl)benzene (DSA-Ph), and a high-band-gap host 2-methyl-9,10-bis(naphthalen-2-yl) anthracene (MADN) as the emission layer with the following structure: ITO/PEDOT:PSS (40 nm)/VB-FNPD (30 nm)/MADN:2% BUBD-1:1% DSA-Ph (50 nm)/TPBI (30 nm)/LiF (0.8 nm)/Al (100 nm)or ITO/PEDOT:PSS (40 nm)/VB-FNPD (30 nm)/MADN:3% BUBD-1 (50 nm)tris(8-hydroxyquinolinato)aluminum (Alq(3); 10 nm)/LiF (0.8 nm)/Al (100 nm). 2,7-disubstituted fluorene-based triaryldiamine(VB-FNPD)is the cross-linking transporting material. The device exhibited a peak current efficiency of 5.67 cd/A for Alq(3) and 5.76 cd/A for TPBI. The device with Alq(3) has operated lifetime seven times higher than the device with TPBI. (C) 2015 Elsevier B.V. All rights reserved.
Blade-coated sol-gel indium-gallium-zinc-oxide for inverted polymer solar cell
(2016-11-01)
Lee, Yan-Huei
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Tsai, Pei-Ting
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Chang, Chia-Ju
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Meng, Hsin-Fei
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Horng, Sheng-Fu
The inverted organic solar cell was fabricated by using sol-gel indium-gallium-zinc-oxide (IGZO) as the electron-transport layer. The IGZO precursor solution was deposited by blade coating with simultaneous substrate heating at 120 degrees C from the bottom and hot wind from above. Uniform IGZO film of around 30 nm was formed after annealing at 400 degrees C. Using the blend of low band-gap polymer poly[(4,8-bis-(2-ethylhexyloxy)-benzo(1,2-b: 4,5-b')dithiophene)-2,6-diyl-alt-(4-(2-ethylhexanoyl)-thieno[3,4-b]thiophene-)-2-6-diyl)] (PBDTTT-C-T) and [6,6]-Phenyl C71 butyric acid methyl ester ([70] PCBM) as the active layer for the inverted organic solar cell, an efficiency of 6.2% was achieved with a blade speed of 180 mm/s for the IGZO. The efficiency of the inverted organic solar cells was found to depend on the coating speed of the IGZO films, which was attributed to the change in the concentration of surface OH groups. Compared to organic solar cells of conventional structure using PBDTTT-C-T: [70]PCBM as active layer, the inverted organic solar cells showed significant improvement in thermal stability. In addition, the chemical composition, as well as the work function of the IGZO film at the surface and inside can be tuned by the blade speed, which may find applications in other areas like thin-film transistors. (C) 2016 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).
Broad band and white phosphorescent polymer light-emitting diodes in multilayer structure
(2008-05-01)
Tang, Kai-Chin
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Tseng, Shin-Rong
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Li, Wei-Shan
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Meng, Hsin-Fei
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Horng, Sheng-Fu
Efficient phosphorescent polymer light-emitting diode with poly(vinylcarbazole) (PVK) doped by two or three iridium complexes in single and bilayer structures are studied. With (tris-(2-4(4-toltyl) phenylpyridine) (Ir(mppy)(3)) as the green emitter and (1-phenylisoquinoline) (acetylacetonate) iridium(III) (Ir(piq)(2)) as the red emitter the efficiency is as high as 23 cd/A with broad band emission from 500 nm to 720 nm. For white emission a second layer is added with blue emitter ((III) bis[(4,-6-di-fluorophenyl-pyridinato)N,C-2] picolinate) (FIrpic) doped in PVK. White light containing three spectral peaks results with efficiency 8.1 cd/A. As the second blue layer is replaced by the fluorescent (poly(9,9-dioctylfluorene)) (PFO) white emission with high color rendering index 86 is achieved. The efficiency is 5.7 cd/A with peak luminance 8900 cd/m(2). For a given iridium complexes ratio the relative intensity of the green and red emission depends sensitively on the second blue layer. (c) 2008 Elsevier B.V. All fights reserved.
Continuous blade coating for multi-layer large-area organic light-emitting diode and solar cell
(2011-11-01)
Chen, Chun-Yu
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Chang, Hao-Wen
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Chang, Yu-Fan
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Chang, Bo-Jie
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Lin, Yuan-Sheng
A continuous roll-to-roll compatible blade-coating method for multi-layers of general organic semiconductors is developed. Dissolution of the underlying film during coating is prevented by simultaneously applying heating from the bottom and gentle hot wind from the top. The solvent is immediately expelled and reflow inhibited. This method succeeds for polymers and small molecules. Uniformity is within 10% for 5 cm by 5 cm area with a mean value of tens of nanometers for both organic light-emitting diode (OLED) and solar cell structure with little material waste. For phosphorescent OLED 25 cd/A is achieved for green, 15 cd/A for orange, and 8 cd/A for blue. For fluorescent OLED 4.3 cd/A is achieved for blue, 9 cd/A for orange, and 6.9 cd/A for white. For OLED with 2 cm by 3 cm active area, the luminance variation is within 10%. Power conversion efficiency of 4.1% is achieved for polymer solar cell, similar to spin coating using the same materials. Very-low-cost and high-throughput fabrication of efficient organic devices is realized by the continuous blade-only method. (C) 2011 American Institute of Physics. [doi:10.1063/1.3636398]
Conversion of absorption to fluorescence probe in solid-state sensor for nitric oxide and nitrite
(2013-04-01)
Hong, Wun-Yan
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Yang, Tsung-Wei
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Wang, Chun-Ming
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Syu, Jia-Hao
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Lin, Yu-Chao
A hydrogel bi-layer structure is used to convert an absorption type to a more convenient fluorescent type probe film for aqueous nitric oxide (NO) and nitrite (NO2-). In the bottom layer the commercial probe molecule 1,2-diaminoanthraquinone (DAQ) is dispersed in poly 2-hydroxyethyl methacrylate (poly HEMA), in the top layer the red inorganic phosphor is dispersed in poly HEMA. Both optical excitation and detection is from the bottom. This bi-layer is integrated with organic light-emitting diode (OLED) and organic photo-detector to form a real-time solid-state sensor. The sensor is responsive to NO bubbling, and remains stable in acid condition. Crown Copyright (C) 2012 Published by Elsevier B.V. All rights reserved.
Current injection and transport in polyfluorene
(2007-08-27)
Yang, Chieh-Kai
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Yang, Chia-Ming
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Liao, Hua-Hsien
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Horng, Sheng-Fu
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Meng, Hsin-Fei
A comprehensive numerical model is established for the electrical processes in a sandwich organic semiconductor device with high carrier injection barrier. The charge injection at the anode interface with 0.8 eV energy barrier is dominated by the hopping among the gap states of the semiconductor caused by disorders. The Ohmic behavior at low voltage is demonstrated to be not due to the background doping but the filaments formed by conductive clusters. In bipolar devices with low work function cathode it is shown that near the anode the electron traps significantly enhance hole injection through Fowler-Nordheim tunneling, resulting in rapid increases of the hole carrier and current in comparison with the hole-only devices. (c) 2007 American Institute of Physics.
Dark carrier recombination in organic solar cell
(2008-09-29)
Wang, Ying-Xuan
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Tseng, Shin-Rong
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Meng, Hsin-Fei
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Lee, Kuan-Chen
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Liu, Chiou-Hua
The carrier recombination in organic solar cells is investigated by numerical modeling to understand the weak dependence of theopen-circuit voltage on the workfunction of the electrodes. In Ohmic contact structures, photocarriers recombine predominantly with dark carriers diffused from the electrode into the semiconductor. Such dark carrier recombination becomes the main limit of power conversion efficiency and open-circuit voltage. For a given semiconductor decreasing the workfunction difference of the electrodes reduces simultaneously the dark carrier recombination and the flat band voltage. The balance between these two opposite factors gives a nearly constant open-circuit voltage. In an ideal bilayer structure there is no dark carrier recombination and the efficiency is demonstrated to be 60% higher than single layer blend. (C) 2008 American Institute of Physics.
Deep blue light-emitting diode based on high molecular weight poly(9,9-dioctylfluorene) with high efficiency and color stability
(2008-06-01)
Tseng, Shin-Rong
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Li, Shiuan-Yi
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Meng, Hsin-Fei
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Yu, Yi-Hsiang
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Yang, Chia-Ming
A highly efficient deep blue polymer light-emitting diode based on poly(9,9-dioctylfluorene) is demonstrated. The performance is found to increase significantly with the molecular weight. Two different molecular weights are compared, one is 71,000 and the other is 365,000. The electroluminescent efficiency and color stability are improved by slightly doping hole traps into the emission layer and bilayer structure. The maximum efficiency is 3.8 cd/A with the corresponding external quantum efficiency of 3.7% at deep blue with Commission Internationale de L'Eclairage (CIE) coordinate at (0.15, 0.09). Stable blue emission is maintained up to 6600 cd/m(2) without growth of green shoulder in emission spectrum. (C) 2007 Elsevier B.V. All rights reserved.
Device having an organic transistor integrated with an organic light-emitting diode's heterojunctions
(2006-06-22)
Meng, Hsin-Fei
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Horng, Sheng-Fu
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Hsu, Chien-Shu
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Liu, Wen-Tsang
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Yang, Yu-Zhong
A device having an organic transistor device integrated with an organic light-emitting diode's heterojunctions. This device at least comprises: a transparent substrate, an organic transistor and an organic light-emitting diode. The organic transistor at least includes an organic semiconductor layer, one of the organic semiconductor layers serves as the organic active layer of the organic light-emitting diode, and the organic active layer and the other organic semiconductor layers form heterojunctions. The present invention uses the organic semiconductor layer to simultaneously form the organic active layer of the organic transistor, so that the organic light-emitting diode and the organic transistor can be easily integrated together so as to solve the problem of the poor luminance efficiency of a conventional integrated organic transistor and organic light-emitting diode and the problem of its high manufacturing cost.
Dynamics and reversibility of oxygen doping and de-doping for conjugated polymer
(2008-05-15)
Liao, Hua-Hsien
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Yang, Chia-Ming
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Liu, Chien-Cheng
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Horng, Sheng-Fu
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Meng, Hsin-Fei
We perform comprehensive long-time monitoring of the p-doping and de-doping of poly(3-hexyl thiophene) under changing external conditions of oxygen, light, and temperature. They are shown to be controlled by the complex adsorption and desorption process with time scales ranging from seconds to weeks. The oxygen doping at atmospheric pressure takes several hours in the dark. The doping is dramatically accelerated to be within seconds with light of wavelength of 500-700 nm. Even at low oxygen pressure of 10(-4) torr doping occurs within minutes with light. The de-doping by oxygen desorption takes as long as weeks at room temperature and vacuum of 10(-4) torr, but when the temperature is raised to near the polymer glass temperature of 370 K, the de-doping is accelerated to minutes as the enhanced chain motion releases the trapped oxygen. Even though visible and near infrared light causes very efficient doping within seconds or minutes depending on vacuum level, such light-induced doping is not a chemical reaction and is fully reversible by thermal annealing at the end without sacrificing the mobility. For the polymer field-effect transistors, only the carrier density is changed while the mobility remains roughly a constant for all the conditions. (c) 2008 American Institute of Physics.
Effect of gate metal on polymer transistor with glass substrate
(2006-12-11)
Meng, Hsin-Fei
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Liu, Chien-Cheng
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Jiang, Chin-Jung
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Yeh, Yu-Lin
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Horng, Sheng-Fu
Poly(3-hexylthiophene) (P3HT) field-effect transistors (FETs) are fabricated on glass substrates with SiO2 as a gate dielectric over the gate. Indium tin oxide (ITO), Al, and Cr are employed as gate metals. For spin-coated FET, the mobility increases from 10(-4)-10(-5) cm(2)/V s for ITO and Al gates to 10(-2) cm(2)/V s for Cr gate. After O-2 plasma treatment, the SiO2 roughness can be made as low as 0.7 nm. The mobility is further improved up to 0.3 cm(2)/V s by dip-coating P3HT. "Crossed rods" such as morphology can be observed in dip-coated FET with high mobility, indicating high degree of self-assembly facilitated by the flat SiO2 surface over Cr gate. (c) 2006 American Institute of Physics.
Efficient inverted organic solar cells without an electron selective layer
(2011)
Wang, Jen-Chun
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Lu, Cheng-Yueh
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Hsu, Jui-Lin
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Lee, Ming-Kun
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Hong, Yun-Ru
Inverted organic solar cells which required no electron selective layer were fabricated and their power conversion efficiency was found to improve irreversibly from 1.46% to 4.10% with post-processing light soaking for 2 hours. X-Ray photoelectron spectroscopy characterization revealed further segregation in surface composition at the interface and was found to explain the current density-voltage measurements. In addition, the light soaked devices were found to exhibit extended lifetime as compared to conventional devices. Since no electron selective layer was required, light soaking may be considered as a cost-effective method to achieve efficient inverted organic solar cells.
Efficient multilayer red fluorescent polymer light-emitting diodes by host and guest blend system
(2010-05-01)
Syu, Wun-Shing
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Lin, Sheng-Chia
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Tseng, Shin-Rong
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Chen, Chun-Yu
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Liu, Chang-Yao
Efficient red light polymer light-emitting diodes are obtained by energy transfer from host and guest blend system. Two kinds of blend systems, SPB02:(10-(2-benzothiazolyl)-1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H,11H-[1] benzopyrano [6,7,8-ij]quinolizin-11-one)(C545T):4-(dicyanomethylene)-2-t-butyl-6-(1,1,7,7-tetramethyljulolidyl-9-enyl)-4H-pyran (DCJTB) and SuperYellow (SY):poly(3,3'''-didodecylquaterthiophene) (PQT-12), are used as the active layers. C545T is a green emitter, acting as an assistant dopant to improve the energy transfer from blue SPB02 host to red DCJTB. The efficiency can achieve to 3.3 cd/A for DCJTB and 3.5 cd/A for PQT-12 system by multilayer device structure with 2,2,2 ''-(1,3,5-phenylene)-tris(1-phenyl-1H-benzimidazole) (TPBi) as electron transport layer. The SuperYellow:PQT-12 device shows great luminance of 16,930 cd/m(2). (C) 2010 Elsevier B.V. All rights reserved.