Browsing by Author "Chen, Chien-Chon"

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A mechanism for the formation of annealed compact oxide layers at the interface between anodic titania nanotube arrays and Ti foil
(2009-06-01)
Chen, Chien-Chon
;
Say, Wen C.
;
Hsieh, Sheng-Jen
;
Diau, Eric Wei-Guang
;
應用化學系
We propose a mechanism for the growth of crystalline anodic titanium-oxide (ATO) nanochannel arrays based on thermodynamic considerations and structural imperfections. Both amorphous and crystalline ATO films were obtained from the anodization of a titanium foil. Amorphous ATO nanotubes have a single-layer form, which makes them inefficient for use in photo-catalytic and solar-cell applications. Annealed ATO nanotubes are considered non-stoichiometric if the effect of oxygen partial pressure on the composition is significant. The driving force behind growing crystalline ATO nanotubes is the drawing of oxygen from the atmosphere to the oxygen site, which consequently decreases the concentration of oxygen vacancies in the anatase phase. The small ionization energies of titanium ions produce the stoichiometric defects. A diagram showing Gibbs energy and Kroger-Vink notation to indicate the strong influence of the non-stoichiometric ATO structure is deduced.
Dye-sensitized solar cell structure and method for fabricating the same
(2010-03-18)
Diau, Eric Wei-Guang
;
Chen, Chien-Chon
;
Chung, Hsien-Wen
;
Chen, Chin-Hsing
;
Sung, Chi-Jui
The present invention discloses a dye-sensitized solar cell structure and a method for fabricating the same. The method of the present invention comprises forming insulation layers on a titanium plate; forming a plurality of titanium dioxide units on the titanium plate each containing a plurality of titanium dioxide nanotubes, wherein each insulation layer is arranged in between two adjacent titanium dioxide units; making the titanium dioxide units absorb a photosensitive dye; forming a transparent conductive film over the insulation layers and the titanium dioxide units; and filling an electrolyte into spaces each enclosed by the transparent conductive film, the titanium dioxide unit, the insulation layers. The present invention not only increases the electron transmission efficiency and photoelectric conversion efficiency but also promote the uniformity of the semiconductor layer.
Fabrication and Characterization of Anodic Titanium Oxide Nanotube Arrays of Controlled Length for Highly Efficient Dye-Sensitized Solar Cells
(2008-12-04)
Chen, Chien-Chon
;
Chung, Hsien-Wen
;
Chen, Chin-Hsing
;
Lu, Hsuch-Pei
;
Lan, Chi-Ming
The performance of dye-sensitized solar cells (DSSC), made of highly ordered anodic titanium oxide (ATO) nanotube (NT) arrays produced directly on Ti foil, depends on the length of these arrays. We controlled these lengths L from 4 to 41 mu m while varying the concentration (0.1, 0.25, 0.5, and 0.8 wt %) of the electrolyte (NH(4)F) in ethylene glycol in the presence of H(2)O (2 vol %) with anodization for various periods (t = 0.5-8 h). The compact and bundle layers introduced. during anodization were effectively removed upon simple ultrasonic cleaning in deionized water containing submicrometer particles of Al(2)O(3) in a small proportion. The photovoltaic performance of the NT-DSSC devices (NH4F at 0.5 wt %) made of ATO films, as prepared, increased from 3.0% to 5.2% as L was increased from 6 mu m (t = 0.5 h) to 30 mu m (t = 8 h). After treatment of the ATO films with TiCl(4) in a two-step annealing process, the optimized NT-DSSC device attained an overall efficiency of 7.0% power conversion.
Fabrication and characterization of eutectic bismuth-tin (Bi-Sn) nanowires
(2009-05-31)
Chen, Shih-Hsun
;
Chen, Chien-Chon
;
Luo, Z. P.
;
Chao, Chuen-Guang
;
材料科學與工程學系
Eutectic Bi-43Sn (in weight percent) nanowires with diameters of 20 nm, 70 nm and 220 nm respectively, were fabricated by a hydraulic pressure injection process using anodic aluminum oxide (AAO) as templates. Novel eutectic microstructure was found within the fabricated nanowires. which are composed of alternating Bi and Sn segments along their wire axes. Within the segments, the electron diffraction analysis revealed single crystalline structures of Bi and Sn elements respectively. Parameters that control the nanowire fabrication process were discussed. It was found out that as the wire diameter reduced, longer Bi and Sn segments formed. (C) 2009 Elsevier B.V. All rights reserved.
Fabrication and characterization of eutectic gold-silicon (Au-Si) nanowires
(2008-09-12)
Lin, Jin-Shyong
;
Chen, Chien-Chon
;
Diau, Eric Wei-Guang
;
Liu, Tzeng-Feng
;
材料科學與工程學系
Hypoeutectic, eutectic and hypereutectic gold-silicon (Au-Si) alloys were synthesized using vacuum smelting. When Au and Si were smelted in a vacuum chamber near 1100 degrees C, Si-(g), Si-2(g), Si-3(g), SiO2(g), Au-(g), SiO2(s) and Au2O3(s) were formed rapidly; the quantities of Au and Si lost were estimated from thermodynamic formulas. The nano- and microstructures of the Au-Si,eutectic compound were characterized with a SEM and a TEM, which showed a discontinuous phase of Si dispersed and mounted within a matrix phase of Au. Cracks that formed about the Au-Si interface made the Au-Si eutectic brittle. From an Au-Si alloy of superior quality as a bulk material, eutectic nanowires of average diameter 60 nm were fabricated after the alloy was melted and injected into an anodic aluminum-oxide (AAO) template. (C) 2008 Elsevier B.V. All rights reserved.
Fabrication of bismuth nanoballs using thermal oil reflow
(2008-11-01)
Kuo, Chin-Guo
;
Chen, Chien-Chon
;
Hsieh, Sheng-Jen
;
Say, Wen C.
;
應用化學系
Sub-micron-size bismuth (Bi) balls with diameters between 100 and 2000 nm were formed on an anodic aluminum oxide (AAO) template using thermal expansion and thermal oil reflow processes. After centrifugal force separation, 100 nm size Bi balls were obtained. In addition, the ball density was approximately 6 x 10(7)/cm(2) on an AAO surface. Because of their round shape, the contact angle of the Bi nanoballs on the AAO surface was large after hot oil reflow, making it easy to remove them using ultrasound and to separate different sizes of balls using centrifugal force. (C) 2008 The Ceramic society of Japan. All rights reserved.
Fabrication of long TiO(2) nanotube arrays in a short time using a hybrid anodic method for highly efficient dye-sensitized solar cells
(2010-01-01)
Li, Lu-Lin
;
Tsai, Chiau-Yiag
;
Wu, Hui-Ping
;
Chen, Chien-Chon
;
Diau, Eric Wei-Guang
We report a simple hybrid anodic method, with initial potentiostatic anodization followed by galvanostatic anodization, to grow much longer titania nanotube ( TNT) arrays in a much shorter anodization period (t). The length of the TNT arrays ( L) depends linearly on t and is controlled by the electric current; the growth rates are 5.3, 10.7 and 20.3 mu m h(-1) for current densities 3.7, 5.6 and 7.5 mA cm(-2), respectively. The produced TNT films of L = 15-57 mu m sensitized with N719 dye were fabricated into devices for photovoltaic characterization. The NT-DSSC devices show systematically improved cell performance depending on L, reflecting the excellent intrinsic light-scattering property of the NT-DSSC devices to harvest increased sunlight with long TNT arrays. The great effective surface area inside TNT arrays has been shown to significantly increase the dye loading, which might help to enhance the cell performance of the device with co-sensitizing of different dyes for improved efficiency of light harvesting in the future. The best performance of the NT-DSSC device was achieved at L similar to 30 mm with a spacer of similar thickness, giving J(SC) = 14.63 mA cm(-2), V(OC) = 0.741 V, FF = 0.70, and eta = 7.6%, which is unprecedented for a back-illumination DSSC.
Fabrication of long TiO2 nanotube arrays in a short time using a hybrid anodic method for highly efficient dye-sensitized solar cells
(2010-01-01)
Li, Lu-Lin
;
Tsai, Chiau-Yiag
;
Wu, Hui-Ping
;
Chen, Chien-Chon
;
Diau, Eric Wei-Guang
We report a simple hybrid anodic method, with initial potentiostatic anodization followed by galvanostatic anodization, to grow much longer titania nanotube ( TNT) arrays in a much shorter anodization period (t). The length of the TNT arrays ( L) depends linearly on t and is controlled by the electric current; the growth rates are 5.3, 10.7 and 20.3 mu m h(-1) for current densities 3.7, 5.6 and 7.5 mA cm(-2), respectively. The produced TNT films of L = 15-57 mu m sensitized with N719 dye were fabricated into devices for photovoltaic characterization. The NT-DSSC devices show systematically improved cell performance depending on L, reflecting the excellent intrinsic light-scattering property of the NT-DSSC devices to harvest increased sunlight with long TNT arrays. The great effective surface area inside TNT arrays has been shown to significantly increase the dye loading, which might help to enhance the cell performance of the device with co-sensitizing of different dyes for improved efficiency of light harvesting in the future. The best performance of the NT-DSSC device was achieved at L similar to 30 mm with a spacer of similar thickness, giving J(SC) = 14.63 mA cm(-2), V-OC = 0.741 V, FF = 0.70, and eta = 7.6%, which is unprecedented for a back-illumination DSSC.
Fluorescence dynamics of zinc protoporphyrin in solution and inside anodized aluminum oxide (AAO) nano-channel arrays
(2006-12-01)
Lin, Jin-Shyong
;
Chen, Yu-Chying
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Chen, Chien-Chon
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Luo, Li-Yang
;
Diau, Eric Wei-Guang
The excited-state relaxation dynamics of zinc protoporphyrin (ZnPP) in THF solution and inside nano-channel arrays of anodized aluminum oxide (AAO) have been investigated with time-correlated single-photon-counting (TCSPC) fluorescence spectra with S-2 excitation (lambda(ex) = 435 nm). We used three initial concentrations of immersion - 4.8 x 10(-6), 4.8 x 10(-5) and 4.8 x 10(-4) M - to examine the extent of aggregation of ZnPP inside the AAO nano-channel arrays of two pore sizes - 15 and 70 nm. Only one decay component corresponds to the aggregation of ZnPP in THF solution, whereas at least two decay components are required to describe the transient behavior of ZnPP inside AAO. The observed systematic variation of the decay coefficients and the corresponding amplitudes of the ZnPP/AAO samples are consistent with the observation of steady-state spectra of the system reported previously (JCCS 2006, 53, 201), but through fluorescence lifetime measurements we further highlight the significance of aggregation of ZnPP in the specific nanoporous environment that is not achievable in ZnPP/THF solutions in large concentrations.
Grooved dye-sensitized solar cell structure and method for fabricating the same
(2010-03-18)
Diau, Eric Wei-Guang
;
Chen, Chien-Chon
;
Chung, Hsien-Wen
;
Chen, Chin-Hsing
;
Sung, Chi-Jui
The present invention discloses a grooved dye-sensitized solar cell structure and a method for fabricating the same. The method of the present invention comprises providing a titanium plate having at least one groove; forming insulation layers on the grooves; forming a plurality of titanium dioxide units on the titanium plate each containing a plurality of titanium dioxide nanotubes, wherein each groove is arranged in between two adjacent titanium dioxide units; making the titanium dioxide units absorb a photosensitive dye; forming a transparent conductive film over the insulation layers and the titanium dioxide units; and filling an electrolyte into spaces each enclosed by the transparent conductive film, the titanium dioxide unit, the insulation layers. The present invention not only increases the electron transmission efficiency and photoelectric conversion efficiency but also promote the uniformity of the semiconductor layer.
Highly Sensitive Arrayed Indium-Antimony Nanowires for Infrared Detection
(2015-01-01)
Chen, Po-Chun
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Chen, Chien-Chon
;
Chen, Shih-Hsun
;
Chou, Chung-Yi
;
Hsieh, Sheng-Jen
The objective of this study is to achieve a high sensitive infrared detector by fabricating highly ordered array of indium-antimony (In-Sb) nanowires which is a semiconductor material. The approach is to investigate an infrared detector with arrayed nanowires which can transport signals in one dimension to obtain high efficiency and sensitivity compared with In-Sb by using traditional thin film fabrications. This research expects to provide an infrared detector by fabricating III-V alloy nanowires to highly improve the resolution of infrared signal. To develop scaled-up functional devices, highly ordered nanowire arrays are essential building blocks. Many candidate materials (metals, alloys, oxides and semiconductors) have been studied for various potential applications in nanotechnology and have shown some promising results. The solid metallic nanowires have been exploited for a wide range of applications to take the advantages of their large length/diameter aspect ratio. Further development to synthesize nanowires efficiently at lower cost is the direction for manufacturing next generation nanodevices. In this study, various diameters of ordering nanowires, from 10 nm to 500 nm, were fabricated and evaluated the performance of the sensitivity of infrared detection. Moreover, a 1 inch plate, which can be regarded as a device, with nanowires array was fabricated by designing a new type of processing chamber.
Method of manufacturing aluminum oxide film with arrayed nanometric pores
(2006-03-09)
Chao, Chuen-Guang
;
Chen, Chien-Chon
;
Chen, Jung-Hsuan
;
Kuo, Chin-Guo
The present invention pertains to a method of manufacturing an aluminum oxide film with arrayed nanometric pores, wherein a commercial aluminum substrate is provided firstly; then the aluminum substrate is annealed and then electro-polished in order to have a mirror-like surface, and then anodized in order to form a aluminum oxide film with a plurality of nanometric pores, which are aligned in array, and then annealed in order that an oxidation reaction can happen thereon and generates oxide, which via self-diffusion, fills some of smaller pores with the pores size being uniformed; lastly a pore-widening is undertaken in order to increase the diameters of the pores. The present invention can accomplish the nanometric pores aligned in array and with an uniform pore diameter, and simultaneously have the advantages of simplified manufacturing process, easier operational control and reduced cost.
Morphologic Characterization of Anodic Titania Nanotube Arrays for Dye-Sensitized Solar Cells
(2010-10-01)
Li, Lu-Lin
;
Tsai, Chiau-Yiag
;
Wu, Hui-Ping
;
Chen, Chien-Chon
;
Diau, Eric Wei-Guang
We report morphologic characterization of the anodic titanium oxide (ATO) films with highly-ordered titania (TiO(2)) nanotube (NT) arrays grown perpendicularly to a titanium (Ti) foil. The length of the ATO arrays was controlled by various electrolytes and anodic periods at a constant applied voltage. In order to enhance the pathways for electron percolation, the ATO film was annealed in an air furnace, forming anatase TiO(2). After TiCl(4) post-treatment to enhance the ruthenium-based dye loading on the ATO surface, the optimized ATO arrays were used as a photoanode in a dye-sensitized solar cell (DSSC). The best performance of the NT-DSSC device was achieved with a NH(4)F-based ATO film at length of 15 pm, giving J(sc) = 12.15 mA cm(-2), V(oc) = 0.74 V, FF = 0.69, and eta = 6.2% under backside illumination.
Photocatalytic effect of anodic titanium oxide nanotubes on various cell culture media
(2011-02-01)
Yu, Chun-Kang
;
Hu, Kan-Hung
;
Wang, Shing-Hoa
;
Hsu, Todd
;
Tsai, Huei-Ting
The use of titanium dioxide (TiO(2)) in photodynamic therapy for the treatment of cancer cells has been proposed following studies of cultured cancer cells. In this work, an ordered channel array of anodic titanium oxide (ATO) was fabricated by anodizing titanium foil. The ATO layer of nanotubes with diameters of 100 nm was made in NH(4)F electrolyte by anodization. The photocatalytic effect of ATO was examined on various culture media by ultraviolet A (UV-A) (366 nm) irradiation. After UV-A irradiation of the ATO layer, redox potential of Tris-HCl buffer (pH 7.5) and dilute acrylamide solution increased instantaneously. The redox potential of the serum-containing RPMI1640 medium also increased dramatically, while that of serum-containing MEM and DMEM media increased slightly. The UVA-induced high redox potential was correlated with the greater ability to break down plasmid DNA strands. These phenomena suggest that a culture medium, such as RPMI1640, with a greater ability to produce free radical may be associated with a stronger photocatalytic effect of ATO on cultured cancer cells reported previously.
Self-cleaning characteristics on a thin-film surface with nanotube arrays of anodic titanium oxide
(2008-08-01)
Chen, Chien-Chon
;
Lin, Jin-Shyong
;
Diau, Eric Wei-Guang
;
Liu, Tzeng-Feng
;
材料科學與工程學系
Self-cleaning of a surface of nanotube arrays of anodic titanium oxide (ATO) is demonstrated. The ATO was prepared in fluoride ion containing sulfate electrolytes with a structure of 0.4 mu m length, 100 nm pores diameter, 120 nm interpore distance, 25 nm pore wall thickness, a 8x10(9) pores cm(-2) pore density, and 68.2% porosity. Prepared as thin films either directly from a Ti foil or on a glass substrate, these arrays have the property that water drops spread quickly over the surface of the films without irradiation. In contrast, a flat anatase TiO2 film requires irradiation with UV light for several minutes before the contact angle decreases to zero. The observed self-cleaning behavior of the ATO thin films is due to the capillary effect of the nanochannel structure and the superhydrophilic property of the anatase TiO2 surface inside the tube.