Browsing by Author "Chen, En-Chen"

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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]
Fabrication and Device Modeling of Micro-textured Conductive Polymer/Silicon Heterojunction Solar Cells
(2012)
Chen, Ting-Gang
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Huang, Bo-Yu
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Huang, Yang-Yue
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Chen, En-Chen
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Yu, Peichen
In this paper, hybrid heterojunction solar cells are demonstrated based on a highly conductive polymer PEDOT:PSS directly spun-cast on an n-type crystalline silicon with microscale surface textures. The fabrication conditions suggest that the organic coverage on the micro-textured surface is excellent and key to achieve high efficiency. The simple solution-based fabrication processes achieved a cell power conversion efficiency of 10.2%. Device modeling had been performed to investigate the interface defect density dependence of cell performances. A power conversion efficiency of above 20% is projected for the hybrid heterojunction cells, showing promises for low-cost photovoltaics.
High performance organic photovoltaic cells with blade-coated active layers
(2012-12-01)
Lim, Siew-Lay
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Chen, En-Chen
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Chen, Chun-Yu
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Ong, Kok-Haw
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Chen, Zhi-Kuan
High performance bulk heterojunction organic photovoltaic (OPV) cells with blade-coated active layers of POD2T-DTBT blended with [6,6]-phenyl-C71-butyric acid methyl ester (PC71BM) are demonstrated in this work. The blade-coated cells exhibit power conversion efficiencies of up to 6.74%, which is comparable to those of conventional spincoated cells but obtained with just a fraction of the material amount used for spincoating. The choice of solvent and the process conditions are manipulated to achieve dense, well-separated morphology which increases the interfacial area for charge dissociation in the blend film. The blade coating technique can be applied in the fabrication of large area, high performance OPV cells with highly efficient materials usage. (C) 2012 Elsevier B.V. All rights reserved.
Highly efficient inverted rapid-drying blade-coated organic solar cells
(2012-04-01)
Chang, Jung-Hao
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Chen, Yi-Hong
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Lin, Hao-Wu
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Lin, Yu-Ting
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Meng, Hsin-Fei
Efficient inverted bulk-heterojunction (BHJ) poly(3-hexylthiophene):[6,6]-phenyl C61 butyric acid methyl ester (P3HT:PCBM) organic solar cells fabricated by rapid-drying blade-coated were demonstrated. Optimized self-organization interpenetration networks and donor/acceptor domain sizes were obtained while maintaining the smooth surface morphology. By integrating with low-temperature-processed sol-gel ZnO electron extraction layer, power conversion efficiency (PCE) up to 4.4% under AM1.5G 1 sun illumination is achieved, compared to fast drying but low efficiency (1.2%) and high efficiency but with long-time solvent annealing treatment (4.3%) control cells deposited by spin coating in chlorobenzene (CB) and 1,2-dichlorobenzene (DCB) solution, respectively. The novel deposition technique reveals a promising process for highly efficient, high throughput, stable morphology organic solar cells fabrication. (c) 2012 Elsevier B.V. All rights reserved.
Increasing organic vertical carrier mobility for the application of high speed bilayered organic photodetector
(2009-11-23)
Tsai, Wu-Wei
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Chao, Yu-Chiang
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Chen, En-Chen
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Zan, Hsiao-Wen
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Meng, Hsin-Fei
The direct influence of the vertical carrier mobility on the frequency response of bilayered organic photodiodes (PDs) is investigated for the first time. With fullerene as the acceptor material, changing vertical hole mobility from 2.3x10(-5) to 2.8x10(-4) cm(2)/V s increases PD bandwidth from 10 to 80 MHz under a 4 V operation. The influence of deposition rate on vertical hole mobility of pentacene film is also discussed. Our results facilitate the application of bilayered organic PDs on the detection of very-high-frequency optical signals.
Infrared proximity sensor using organic light-emitting diode with quantum dots converter
(2012-11-01)
Chen, En-Chen
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Yeh, Han-Cheng
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Chao, Yu-Chiang
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Meng, Hsin-Fei
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Zan, Hsiao-Wen
An efficient visible-to-infrared conversion film is made by blending CdTe quantum dots (CdTe QDs) of 12 nm diameter in a polyvinylpyrrolidone 360 (PVP 360) polymer matrix cast by water solution. The solid-state photoluminescence quantum efficiency exceeds 10% with emission peak at 810 nm. Strong 810 emission is obtained by combining the quantum dot film and a green polyfluorene light-emitting diode. Color filter is used to remove residual light below 780 nm to make it entirely invisible. Infrared photo-detector is made by blending poly[5-(5-(2,5-bis(decyloxy)-4-methylphenyl)thiophen-2-yl)-2,3-bis(4-(2-ethylhexyloxy)phenyl)-7-(5-methylthiophen-2-yl)thieno[3,4-b]pyrazine] (PBDOTTP) with band-gap 1.2 eV and (6,6)-phenyl-C61-butyric acid methyl ester (PCBM). The pixel contains one PD surrounded by four PLED on its four sides. The active areas of the five devices are all I cm by 1 cm and they are on the same plane. Infrared proximity sensor with photo-current over 300 nA at 10 cm object distance is achieved by detecting the reflected infrared signal. (C) 2012 Elsevier B.V. All rights reserved.
ITO-free inverted polymer solar cell on metal substrate with top-illumination
(2014-01-01)
Chen, En-Chen
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Tsai, Pei-Ting
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Tsai, Chia-Ying
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Chang, Jung-Hao
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Huang, Zheng-Yu
High-performance polymer solar cells are conventionally fabricated on the rigid and costly indium-tin-oxide (ITO) glass substrates, which are incompatible with the roll-to-roll process with low cost. This study shows that polymer solar cells can be made on ITO-free flexible stainless steel with only a moderate compromise in power conversion efficiency. A blend of poly (3-hexylthiophene) (P3HT) and (6,6)-phenyl-C61-butyric acid methyl ester (PCBM) was used as the active material for the inverted structure. The bottom electrode was an alloy of Al and Au spontaneously formed from a bi-layer during thermal annealing of the active layer. This alloy had a low work function of 3.9 eV, and a high resistance to oxide formation throughout the entire process. Semi-transparent Ag was used as the top electrode. These solar cells on stainless steel had an efficiency of 2.6%. The majority of the loss came from the top electrode transmission at approximately 60%. This all-metal approach makes roll-to-roll polymer cell fabrication possible. (C) 2013 Elsevier B.V. All rights reserved.
Micro-textured conductive polymer/silicon heterojunction photovoltaic devices with high efficiency
(1970-01-01)
Chen, Ting-Gang
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Huang, Bo-Yu
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Chen, En-Chen
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Yu, Peichen
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Meng, Hsin-Fei
"In this work, hybrid heterojunction solar cells are demonstrated based on a conjugate polymer poly(3,4-ethylenedioxy-thiophene):poly(styrenesulfonate) (PEDOT:PSS) directly spun-cast on micro-textured n-type crystalline silicon wafers. The fabrication conditions suggest that the organic coverage on the micro-textured surface is excellent and key to achieve high efficiency, leading to an average power conversion efficiency of 9.84%. A one-dimensional drift-diffusion model is then developed based on fitting the device characteristics with experimentally determined PEDOT: PSS parameters and projects an ultimate efficiency above 20% for organic/inorganic hybrid photovoltaics. The simulation results reveal the impacts of defect densities, back surface recombination, doping concentration, and band alignment. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4734240]"
Multilayer rapid-drying blade coating for organic solar cells by low boiling point solvents
(2014-06-01)
Chen, En-Chen
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Tsai, Pei-Ting
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Chang, Bo-Jie
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Wang, Chun-Ming
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Meng, Hsin-Fei
A bulk heterojunction organic solar cell with poly(3-hexylthiophene) (P3HT) as the donor and (6,6)-phenyl-C61-butyric acid methyl ester (PCBM) as the acceptor is deposited using blade coating on a hot plate at 80 degrees C with hot air of 70 degrees C applied from above. In contrast to the 30 min of conventional dichlorobenzene solvent annealing, the rapid-drying blade coating forms a dry film in 1 s. The fabrication throughput is substantially enhanced. The blade-coated film has a smoother surface roughness of 3.5nm compared with 10.5nm for solvent annealing; however, the desired phase separation in the 50nm scale forms despite the rapid drying. A single layer solar cell exhibits power conversion efficiency of 4.1% with blade coating in chlorobenzene, which is the same as solvent annealing device. A multilayer device with carrier blocking layers fabricated entirely of the less toxic toluene also exhibits efficiency of 4.1%. (C) 2014 The Japan Society of Applied Physics
New Thiophene-Phenylene-Thiophene Acceptor Random Conjugated Copolymers for Optoelectronic Applications
(2010-06-01)
Tsai, Jung-Hsun
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Chueh, Chu-Chen
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Chen, Wen-Chang
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Yu, Chao-Ying
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Hwang, Gue-Wuu
New low band gap thiophene-phenylene-thiophene (TPT)-based donor-acceptor-donor random copolymers were synthesized for optoelectronic device applications by a palladium-catalyzed Stille coupling reaction under microwave heating. The acceptors included 2,3-bis(4-(2-ethylhexyloxy)phenyl)-5,8-bis[5'-bromo-dithien-2-yl-quinoxalines] (DTQ) and 3,6-bis(5-bromothiophen-2-yl)-2,5-bis(2-ethyl-hexyl)-pyrrolo[3,4-c]-pyrrole-1,4-dione (DPP). The prepared random copolymers were named as PTPTDTQ(0.55), PTPTDTQ(0.34)DPP(0.14), and PTPTDTQ(0.26)DPP(0.34) depending on the copolymer ratio. The optical band gaps (Er) of PTPTDTQ(0.55), PTPTDTQ(0.34)DPP(0.14), and PTPTDTQ(0.26)DPP(0.34) were 1.74, 1.56, and 1.48 eV, respectively. The hole mobility obtained from the field-effect transistor devices prepared from PTPTDTQ(0.55), PTPTDTQ(0.34)DPP(0.14), and PTPTDTQ(0.26)DPP(0.34) were 2.2 x 10(-3), 2.4 x 10(-3), and 4.7 x 10(-3) cm(2) V s(-1), respectively, with the on-off ratios of 4.0 x 10(4), 4.0 x 10(4), and 5.3 x 10(4). It suggested that the significant intramolecular charge transfer between the TPT and acceptor led to the band gap reduction and hole mobility enhancement. Polymer solar cells of these TPT-based copolymers blended with 1-(3-methoxycarbonyl)propyl-1-phenyl-[6,6]-C-71 (PC(71) BM) under illumination of AM 1.5G (100 mW cm(-2)) solar simulator exhibited a power conversion efficiency (PCE) as high as 3.71%. Besides, the near-infrared photodetector device prepared from PTPTDTQ(0.26)DPP(0.34) showed a high external quantum efficiency exceeding 32% at 700 nm (under -3 V bias) and fast-speed response. This study suggests that the prepared TPT-based donor-acceptor random copolymers exhibited promising and versatile applications on optoelectronic devices. (C) 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 2351-2360, 2010
Optimal design and fabrication of ITO/organic photonic crystals in polymer light-emitting diodes using a focused ion beam
(2010-05-01)
Tsai, Che-Hung
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Liao, Lun-De
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Luo, Yi-Shiun
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Chao, Paul C. -P.
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Chen, En-Chen
This study aims to achieve high directionality and large extraction of light emission from polymer light-emitting diodes via optimizing photonic crystals (PCs). The optimization is achieved through the optical modeling using a 3D finite-difference time-domain (FDTD) method and the intelligent numerical optimization technique, genetic algorithm (GA). In results, the PC period, depth and filling factor can be found. The FDTD method has been proven very effective for modeling complex multilayer PLED devices in which the electron-transporting layer is only a few tens of nanometers away from a metallic layer. On the other hand, GA is a powerful tool to cope with a complicated optimization problem with multiple variables to optimize. The optimized PCs are later fabricated by focused ion beams (FIB) for the PLED. With desired PCs, an increase of the extraction efficiency in excess of 46% is achieved experimentally and the 3D FDTD calculation explains this result faithfully. (C) 2009 Elsevier B.V. All rights reserved.
ORGANIC PHOTOSENSITIVE OPTOELECTRONIC DEVICE
(2010-11-11)
Meng, Hsin- Fei
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Hong, Sheng-Fu
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Tseng, Hsin-Rong
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Chen, En-Chen
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Chu, Chia-Hung
An organic photosensitive optoelectronic device includes an anode, an organic photosensitive layer formed on the anode and having a donor portion and an acceptor portion, a hole blocking layer formed on the organic photosensitive layer so as for the organic photosensitive layer to be sandwiched between the anode and the hole blocking layer, and a cathode formed on the hole blocking layer so as for the hole blocking layer to be sandwiched between the cathode and the organic photosensitive layer. The highest occupied molecular orbitals (HOMO) of the hole blocking layer is at least 0.3 eV higher than that of the donor portion. Therefore, the optoelectronic device efficiently suppresses dark current so as to enhance sensitivity when applied to a detector.
Organic semiconductor infrared distance sensing apparatus and organic infrared emitting apparatus thereof
(2010-06-03)
Meng, Hsin-Fei
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Horng, Sheng-Fu
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Tseng, Hsin-Rong
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Yang, Chia-Ming
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Chen, En-Chen
An organic semiconductor infrared distance sensing apparatus and an organic infrared emitting apparatus thereof are disclosed. The organic semiconductor infrared distance sensing apparatus comprises an organic infrared emitting apparatus and an organic infrared receiving apparatus. The organic infrared emitting apparatus has a positive electrode layer and a negative electrode layer to form an electric field, and organic light emitting molecules are sandwiched between the two layers and correspond to the positive electrode layer and the negative electrode layer. Under a positive bias, a plurality of electrons and holes are respectively injected from electrodes and recombine with each other to emit photons. An infrared organic conversion layer absorbs and transfers the energy to infrared emitting molecules to emit infrared light. The organic infrared receiving apparatus receives the infrared light reflected by an obstacle to generate photocurrent which varies with distance, thereby sensing the distance between the obstacle and the apparatus.
Polymer infrared photo-detector with high sensitivity up to 1100 nm
(2011-08-01)
Chen, En-Chen
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Tseng, Shin-Rong
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Chao, Yu-Chiang
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Meng, Hsin-Fei
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Wang, Chih-Feng
We reported a low band-gap conjugated polymer, poly[2,3-bis(4-(2-ethylhexyloxy)phenyl)-5,7-di(thiophen-2-yl)thienol[3,4-b]pyrazine] (PDTTP), was studied for the near infrared (NIR) photo-detector application. PDTTP shows intense absorption in NIR wavelength (to 1000 nm) and the estimated optical and electrochemical band-gaps of PDTTP are quite small around 1.15 eV and 1.08 eV, respectively. The low band-gap and the extended long wavelength absorption originates from the introduction of alternating TP units when its parent polythieno[3,4-b]pyrazine shows excellent narrow band-gap properties. Therefore, the relatively low band-gap and intense absorption in long wavelength of PDTTP make itself a promising candidate for near-infrared photo-detector. The hole mobility of the PDTTP measured from the bottom contact field effect transistor is around 1.40 x 10(-3) cm(2)/V s with a on/off ratio of 2100. The photo-detector based on bulk hetero-junction PDTTP and (6,6)-phenyl-C61-butyric acid methyl ester blend (PCBM) has the incident photon-to-electron conversion efficiency 28.9% at 1000 nm (-5 V) and 6.2% at 1100 nm (-5 V). This photo-detector can be operated at a high-speed of 1 MHz. The experimental result suggests the potential applications of low band-gap conjugated polymers on near-infrared photo-detectors. (C) 2011 Elsevier B.V. All rights reserved.
Polymer infrared proximity sensor
(2008-08-11)
Chen, En-Chen
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Tseng, Shin-Rong
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Ju, Jia-Hong
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Yang, Chia-Ming
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Meng, Hsin-Fei
A proximity sensor that combines a polymer light-emitting diode and a polymer photodiode is presented. The operation wavelength is in the near infrared from 700 to 850 nm. The infrared emission is obtained by adding a color conversion film of polyvinylpyrrolidone polymer matrix blended with infrared dye 1,1-diethyl-2,2-dicarbocyanine iodide to a red polymer light-emitting diode. The photodetector relies on the direct charge-transfer exciton generation in a donor-acceptor polymer blend of poly(3-hexylthiophene) and (6,6)-phenyl-C(61)-butyric acid methyl ester. The detection distance is up to 19 cm for objects with various colors and roughness under ambient indoor lighting. (C) 2008 American Institute of Physics.
Polymer Infrared Proximity Sensor Array
(2011-04-01)
Chen, En-Chen
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Shih, Cheng-Yang
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Dai, Ming-Zhi
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Yeh, Han-Cheng
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Chao, Yu-Chiang
A near-infrared proximity sensor array is achieved by integrating a polymer light-emitting diode and a polymer photodetector (PD). A green emission is converted into deep red peaked at 670 nm by the inorganic phosphor Intematix R670 with quantum efficiency of over 20%. A bandpass filter is used to select a spectral tail of phosphor luminescence with a wavelength above 700 nm. The emissive polymer is green polyfluorene. The infrared PD contains a thick film of a blend of poly(3-hexylthiophene) and (6,6)-phenyl-C61-butyric acid methyl ester up to a thickness of 8 mu m. Position of a moving object at a distance of 10 cm is detected in real time by the array with dynamic images displayed on the computer screen.
Polymer solar cell by blade coating
(2009-08-01)
Chang, Yu-Han
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Tseng, Shin-Rong
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Chen, Chun-Yu
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Meng, Hsin-Fei
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Chen, En-Chen
Polymer bulk hetero-junction solar cells of poly(3-hexylthiophene) (P3HT) donor and (6,6)-phenyl-C61-butyric acid methyl ester (PCBM) acceptor are fabricated by blade coating in toluene solution. Desired donor-acceptor self-organization is achieved without the slow drying process and high boiling point solvent. Power conversion efficiency is 3.8%. much higher than the 2.6% obtained by spin coating in toluene solution. The blade coating method has nearly 100% material usage and can be integrated in the roll-to-roll process with high throughput production. (C) 2009 Elsevier B.V. All rights reserved.
Solution-processed Silicon Hybrid Heterojunction Photovoltaics with Silver Nanowires
(2012-01-01)
Huang, Bo-Yu
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Liu, Hsiao-Wei
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Chen, Ting-Gang
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Chen, En-Chen
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Chen, Bo-han
An Organic/inorganic hybrid solar cells are cheap alternatives to conventional silicon-based solar cells. The devices take the advantages of high optical absorption and carrier mobility of inorganic semiconductors, while maintaining the easy processing attributes of polymers or other soft materials. However, the conduction of holes has been a major technical barrier for the advance of such novel devices. In this study, we propose the use of silver nanowires (AgNWs) to improve the series resistance of the hybrid solar cells and further to realize solution-processed silicon-based photovoltaics. The hybrid silicon heterojunction solar cells are demonstrated based on the composite of conductive polymer PEDOT:PSS directly spun-cast on a micro-textured n-type crystalline silicon wafer, followed by the Meyer rod coating of AgNWs as the frontal metal contacts. The cross linked AgNWs offer high transparency and low sheet resistance, which can be easily fabricated using low-cost and non-toxic materials. Moreover, the industrial-standard microscale surface textures improve the antireflection and carrier collection without increasing much surface recombination. As a result, the device current density-voltage characteristics reveals a high power conversion efficiency of 6.8% under a calibrated illumination intensity of 1000 W/m(2) of the AM1.5G solar spectrum, shedding light into the attainment of rapid solution processed silicon hybrid heterojunction solar cells.