Browsing by Author "Su, Ming-Shin"

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An Organic Hole Transport Layer Enhances the Performance of Colloidal PbSe Quantum Dot Photovoltaic Devices
(2010-10-22)
Kuo, Chih-Yin
;
Su, Ming-Shin
;
Hsu, Yu-Chien
;
Lin, Hui-Ni
;
Wei, Kung-Hwa
A thin poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) hole transport layer enhances the AM1.5 power conversion efficiency of a PbSe quantum dot (QD)-containing photovoltaic device to 2.4%, from 1.5% for a standard PbSe QD device, a relative increase of 60%. Synchrotron X-ray reflectivity measurements reveal that the roughness of the interfaces between the various layers decreases dramatically in the presence of the PEDOT: PSS layer. In addition, the device life time under continuous simulated AM1.5 irradiation (100 mW cm(-2)), measured in terms of the time required to reach 80% of the normalized efficiency, for the PbSe QD device incorporating the PEDOT:PSS hole transport layer is six times longer than that of the standard PbSe QD device.
An Organic Hole Transport Layer Enhances the Performance of Colloidal PbSe Quantum Dot Photovoltaic Devices
(2010-10-22)
Kuo, Chih-Yin
;
Su, Ming-Shin
;
Hsu, Yu-Chien
;
Lin, Hui-Ni
;
Wei, Kung-Hwa
A thin poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) hole transport layer enhances the AM1.5 power conversion efficiency of a PbSe quantum dot (QD)-containing photovoltaic device to 2.4%, from 1.5% for a standard PbSe QD device, a relative increase of 60%. Synchrotron X-ray reflectivity measurements reveal that the roughness of the interfaces between the various layers decreases dramatically in the presence of the PEDOT: PSS layer. In addition, the device life time under continuous simulated AM1.5 irradiation (100 mW cm(-2)), measured in terms of the time required to reach 80% of the normalized efficiency, for the PbSe QD device incorporating the PEDOT:PSS hole transport layer is six times longer than that of the standard PbSe QD device.
Competition between Fullerene Aggregation and Poly(3-hexylthiophene) Crystallization upon Annealing of Bulk Heterojunction Solar Cells
(2011-08-01)
Wu, Wei-Ru
;
Jeng, U-Ser
;
Su, Chun-Jen
;
Wei, Kung-Hwa
;
Su, Ming-Shin
Concomitant development of [6,6]-phen-C(61)-butyric acid methyl ester (PCBM) aggregation and poly(3-hexylthiophene) (P3HT) crystallization in bulk heterojunction (BHJ) thin-film (ca. 85 nm) solar cells has been revealed using simultaneous grazing incidence small-/wide-angle X-ray scattering (GISAXS/GIWAXS). With enhanced time and spatial resolutions (5 s/frame; minimum q approximate to 0.004 angstrom(-1)), synchrotron GISAXS has captured In detail the fast growth in size of PCBM aggregates from 7 to 18 nm within 100 s of annealing at 150 degrees C. Simultaneously observed is the enhanced crystallization of P3HT Into lamellae oriented mainly perpendicular but also parallel to the substrate. An Avrami analysis of the observed structural evolution indicates that the faster PCBM aggregation follows a diffusion-controlled growth process (confined by P3HT segmental motion), whereas-the slower development of crystalline P3HT nanograins is characterized by constant nucleation rate (determined by the degree. of supercooling and POW demixing). These two competing kinetics result in local phase separation with space filling PCBM and P3HT nanodomains less than 20 nm in size when annealing temperature is kept below 180 degrees C. Accompanying the morphological development is the synchronized Increase In electron and hole mobilities of the BHJ thin-film solar cells, revealing the sensitivity of the carrier transport of the device on the structural features of PCBM and P3HT nanodomains. Optimized structural parameters, including the aggregate size and mean spacing of the PCBM aggregates, are quantitatively correlated to the device performance; a comprehensive network structure of the optimized BHJ thin film is presented.
Competition between PCBM Aggregation and P3HT crystallization in thin films upon annealing
(2011-01-01)
Jeng, U-Ser
;
Wu, Wei-Ru
;
Su, Chun-Jen
;
Wei, Kung-Hwa
;
Su, Ming-Shin
Crystalline conjugated polymer containing fused 2,5-di(thiophen-2-yl)thieno[2,3-b]thiophene and thieno[3,4-c]pyrrole-4,6-dione units for bulk heterojunction solar cells
(2011-01-01)
Chen, Guan-Yu
;
Cheng, Yu-Hsin
;
Chou, Yi-Jen
;
Su, Ming-Shin
;
Chen, Chia-Min
A new conjugated polymer, PDTTTPD, comprising 2,5-di-(thiophen-2-yl)thieno[3,2-b]thiophene and thieno[3,4-c]pyrrole-4,6-dione units, exhibits high crystallinity and excellent thermal stability. A device incorporating PDTTTPD and [6,6]-phenyl-C(71)-butyric acid methyl ester (1 : 1, w/w) exhibited a power conversion efficiency of 5.1%.
Crystalline conjugated polymer containing fused 2,5-di(thiophen-2-yl)thieno[2,3-b]thiophene and thieno[3,4-c]pyrrole-4,6-dione units for bulk heterojunction solar cells
(2011-01-01)
Chen, Guan-Yu
;
Cheng, Yu-Hsin
;
Chou, Yi-Jen
;
Su, Ming-Shin
;
Chen, Chia-Min
A new conjugated polymer, PDTTTPD, comprising 2,5-di-(thiophen-2-yl)thieno[3,2-b]thiophene and thieno[3,4-c]pyrrole-4,6-dione units, exhibits high crystallinity and excellent thermal stability. A device incorporating PDTTTPD and [6,6]-phenyl-C(71)-butyric acid methyl ester (1 : 1, w/w) exhibited a power conversion efficiency of 5.1%.
Distribution of Crystalline Polymer and Fullerene Clusters in Both Horizontal and Vertical Directions of High-Efficiency Bulk Heterojunction Solar Cells
(2013-06-26)
Liu, Chih-Ming
;
Su, Ming-Shin
;
Jiang, Jian-Ming
;
Su, Yu-Wei
;
Su, Chun-Jen
In this study, we used (i) synchrotron grazing-incidence small-/wide-angle X-ray scattering to elucidate the crystallinity of the polymer PBTC12TPD and the sizes of the clusters of the fullerenes PC61BM and ThC61BM and (ii) transmission electron microscopy/electron energy loss spectroscopy to decipher both horizontal and vertical distributions of fullerenes in PBTC12TPD/fullerene films processed with chloroform, chlorobenzene and dichlorobezene. We found that the crystallinity of the polymer and the sizes along with the distributions of the fullerene clusters were critically dependent on the solubility of the polymer in the processing solvent when the solubility of fullerenes is much higher than that of the polymer in the solvent. In particular, with chloroform (CF) as the processing solvent, the polymer and fullerene units in the PBTC12TPD/ThC61BM layer not only give rise to higher crystallinity and a more uniform and finer fullerene cluster dispersion but also formed nanometer scale interpenetrating network structures and presented a gradient in the distribution of the fullerene clusters and polymer, with a higher polymer density near the anode and a higher fullerene density near the cathode. As a result of combined contributions from the enhanced polymer crystallinity, finer and more uniform fullerene dispersion and gradient distributions, both the short current density and the fill factor for the device incorporating the CF-processed active layer increase substantially over that of the device incorporating a dichlorobenzene-processed active layer; the resulting power conversion efficiency of the device incorporating the CF-processed active layer was enhanced by 46% relative to that of the device incorporating a dichlorobenzene-processed active layer.
Embedded indium-tin-oxide nanoelectrodes for efficiency and lifetime enhancement of polymer-based solar cells
(2010-04-12)
Yu, Peichen
;
Chang, Chia-Hua
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Su, Ming-Shin
;
Hsu, Min-Hsiang
;
Wei, Kung-Hwa
In this paper, distinctive indium-tin-oxide (ITO) nanorods are employed to serve as buried electrodes for polymer-based solar cells. The embedded nanoelectrodes allow three-dimensional conducting pathways for low-mobility holes, offering a highly scaffolded cell architecture in addition to bulk heterojunctions. As a result, the power conversion efficiency of a polymer cell with ITO nanoelectrodes is increased to about 3.4% and 4.4% under one-sun and five-sun illumination conditions, respectively, representing an enhancement factor of up to similar to 10% and 36% compared to a conventional counterpart. Also, the corresponding device lifetime is prolonged twice as much to about 110 min under five-sun illumination.
Improving Device Efficiency of Polymer/Fullerene Bulk Heterojunction Solar Cells Through Enhanced Crystallinity and Reduced Grain Boundaries Induced by Solvent Additives
(2011-08-02)
Su, Ming-Shin
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Kuo, Chih-Yin
;
Yuan, Mao-Chuan
;
Jeng, U-Ser
;
Su, Chun-Jen
The power conversion efficiency of a device incorporating a crystalline polymer/fullerene thin film improves from 5% to 7.3% - a relative increase of 45% - when an additive, diiodohexane (DIH), is present during processing. The DIH-processed active layer exhibits substantially enhanced polymer crystallinity and smaller fractal-like fullerene clusters.
In situ electrochemical doping enhances the efficiency of polymer photovoltaic devices
(2011)
Su, Ming-Shin
;
Su, Hai-Ching
;
Kuo, Chih-Yin
;
Zhou, Yi-Ren
;
Wei, Kung-Hwa
In this study, we found that the formation of a p-i-n junction through in situ electrochemical doping is a promising way to enhance the performance of polymer photovoltaic devices. We applied a pre-bias to metal triflate [LiOTf, KOTf, Ca(OTf)(2), Zn(OTf)(2)]/poly(ethylene oxide) (PEO)-incorporated poly[5-(2'-ethylhexyloxy)-2-methoxy-1,4-phenylenevinylene] (MEH-PPV)/{6}-1-(3-(methoxycarbonyl) propyl)-{5}-1-phenyl-[5,6]-C(61) (PCBM) photovoltaic devices to form p-i-n junctions in their active layers. Auger depth profile analyses and alternating-current capacitance analyses of these doped devices revealed that the positive and negative ions were distributed unequally to form an asymmetrical p-i-n structure in a thin layer of ca. 100 nm of the polymer, and the intrinsic layer became thinner when formed under a higher pre-bias voltage. Atomic force microscopy and transmission electron microscopy revealed that the addition of metal triflate/PEO to MEH-PPV/PCBM improved the morphology of the composite films. Among the various doped devices, the MEH-PPV/PCBM device incorporating a LiOTf/PEO mixture exhibited the highest power conversion efficiency, a 40% increase relative to that of the reference device (MEH-PPV/PCBM).
Ligands affect the crystal structure and photovoltaic performance of thin films of PbSe quantum dots
(2011)
Kuo, Chih-Yin
;
Su, Ming-Shin
;
Ku, Ching-Shun
;
Wang, Shu-Min
;
Lee, Hsin-Yi
We have prepared thin films of PbSe quantum dots (QDs) featuring three different ligands, oleic acid (OA), butylamine (BA), and 1,2-ethanedithiol (EDT), which have pronounced affects on the arrangement and photovoltaic performance of the PbSe QDs in the thin films. Transmission electron microscopy revealed that ligands that altered the inter-QD spacing induced significant changes in the packing of the PbSe QDs in localized regions of small areas (300 x 300 nm) of the thin films: from a superlattice of OA-capped PbSe QDs to a chaotic pattern of EDT-capped PbSe QDs. Using a synchrotron X-ray reflectivity probe and data fitting, we determined that the roughness decreased and the average densities increased for large-area (1.5 x 1.5 cm) PbSe QD thin films capped with BA and EDT, relative to those of the OA-capped PbSe QD film. In particular, the PbSe QDs' vertical packing density, which is critical for charge transport, increased substantially for the system incorporating EDT ligands. As a result, devices containing the EDT-treated PbSe QD film as the active layer displayed much improved power conversion efficiencies (PCEs) relative to those of corresponding devices featuring either the OA-or BA-capped PbSe QD films as active layers. Adopting a layer-by-layer technique, we fabricated a EDT-capped PbSe QD device that exhibited a PCE of 2.45%.
Morphologies of Self-Organizing Regioregular Conjugated Polymer/Fullerene Aggregates in Thin Film Solar Cells
(2010-01-12)
Chiu, Mao-Yuan
;
Jeng, U-Ser
;
Su, Ming-Shin
;
Wei, Kung-Hwa
;
材料科學與工程學系
In this study, We used simultaneous synchrotron grazing incidence X-ray scattering and diffraction to elucidate the overall morphologies of bulk heterojunction (BHJ) thin film (ca. 100 nm) solar cells containing phase-separated poly(3-hexylthiophene) (P3HT) and [6,6]-phertyl-C(61)-butyric acid methyl ester (PCBM) domains. Specifically, the dimensions and orientation of the P3HT crystallites and the sizes of the PCBM aggregates in BHJ thin films were determined. The appropriate PCBM aggregate size and density required for all optimum performance of the film in the photovoltaics device resulted in deteriorated ordering in the out-of-plane direction, but improved the in-plane packing of the P3HT lamellae. When the P3HT crystallites and PCBM aggregates had comparable domain sizes and number densities, the interpercolated networks for electron- and hole-transport were optimized in the film. This new understanding of the underlying mechanism of carrier mobility in BHJ thin films might be crucial in improving the efficiency of future solar cells.
Synthesis and Characterization of Donor-Acceptor Poly(3-hexylthiophene) Copolymers Presenting 1,3,4-Oxadiazole Units and Their Application to Photovoltaic Cells
(2010-08-01)
Wang, Hsu-Shen
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Su, Ming-Shin
;
Wei, Kung-Hwa
;
材料科學與工程學系
;
Department of Materials Science and Engineering
We have used Grignard metathesis polymerization to prepare poly(3-hexylthiophene)-based copolymers containing electron-withdrawing 4-tert-butylphenyl-1,3,4-oxadiazole-Phenyl moieties as side chains. We characterized these copolymers using (1)H and (13)C nuclear magnetic resonance spectroscopy, thermogravimetric analysis, and gel permeation chromatography. The band gap energy of copolymer was determined from the onset of the optical absorption. The quenching effects were observed in the photoluminescence spectra of the copolymers incorporating pendant electron-deficient 1,3,4-oxadiazole moieties on the side chains. The photocurrents of devices were enhanced in the presence of an optimal amount of the 1,3,4-oxadiazole moieties, thereby leading to improved power conversion efficiencies. (C) 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3331-3339, 2010
Three-dimensional indium-tin-oxide electrode, method of fabricating the same, device of fabricating the same, and method of fabricating solar cell comprising the same
(2010-12-09)
Chang, Chia-Hua
;
Yu, Pei-Chen
;
Hsu, Min-Hsiang
;
Wei, Kung-Hwa
;
Su, Ming-Shin
A three-dimensional ITO electrode and the method of fabricating the same are disclosed. The three-dimensional ITO electrode of the present invention has a conductive layer and a plurality of ITO nanorods formed on the conductive layer, wherein the length range of the ITO nanorods can vary from 10 nm to 1500 nm. The best length is about 50 nm-200 nm for organic solar cells. When applied into organic optoelectronic devices such as organic solar cells and organic light-emitting diodes (OLEDs), the three-dimensional structure of the ITO electrode may increase the contact area to the active layer, thus improving the electric current collecting efficiency and uniformity of current spreading (flowing). Also, an evaporator, a solar cell comprising the above three-dimensional ITO electrode, and the method of fabricating the solar cell are disclosed.