Browsing by Author "Dong, Rui-Xuan"

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High performance dye-sensitized solar cells based on platinum nanoparticle/multi-wall carbon nanotube counter electrodes: The role of annealing
(2012-04-01)
Huang, Kuan-Chieh
;
Wang, Ying-Chiao
;
Chen, Po-Yen
;
Lai, Yi-Hsuan
;
Huang, Jen-Hsien
A composite film is coated on the FTO using a solution, containing a synthesized dispersant, poly(oxyethylene)-segmented imide (POEM), dihydrogen hexachloroplatinate (H2PtCl6), and multi-wall carbon nanotube(MWCNT); the thus coated FTO is used as the counter electrode (CE) for a dye-sensitized solar cell (DSSC). The annealing temperature of the composite film, in the range of 110-580 degrees C, is found to be crucial for optimizing its catalytic ability to obtain the best possible performance for the DSSC. About 47% loss in mass for the POEM/H2PtCl6/MWCNT composite is observed from 110 to 390 degrees C, due to not only the progressive formation of PtNPs from H2PtCl6 but the decomposition of POEM. Therefore, the efficiencies (eta) of DSSCs applying these CEs are enhanced from 1.28 +/- 0.08% (110 degrees C) to 8.47 +/- 0.21% (390 degrees C). The mass of the composite loses dramatically under heating above 390 degrees C, due to the decomposition of MWCNTs. The eta decreases to 7.77 +/- 0.15% at 450 degrees C because the decrease in surface roughness of film. PtNPs grow in sizes from 450 to 580 degrees C, resulting in the further decrease in catalytic ability of film and the observed eta from 7.77 +/- 0.15% to 7.19 +/- 0.21%. (C) 2011 Elsevier B.V. All rights reserved.
Synthesis and characterization of polyimide-silica nanocomposites using novel fluorine-modified silica nanoparticles
(2007-04-15)
Mo, Te-Cheng
;
Wang, Hong-Wen
;
Chen, San-Yan
;
Dong, Rui-Xuan
;
Kuo, Chien-Hung
Polyimide-silica nanocomposites were synthesized with 4,4'-oxydianiline, 4,4'-(4,4'-isopropylidenediphenoxy)bis(phthalic anhydride), and fluorine-modified silica nanoparticles. Fluorinated precursors such as 4",4'"-(hexafluoroisopropylidene)bis(4-phenoxyaniline) (6FBPA) and 4,4'-(hexafluoroisopropylindene)diphenol (BISAF) were employed to modify the surface of the silica nanoparticles. The microstructures and thermal, mechanical, and dielectric properties of the polymide-silica nanocomposites were investigated. An improvement in the thermal stability and storage modulus of the polyimide nanocomposites due to the addition of the modified silica nanoparticles was observed. The microstructures of the polyimide-silica nanocomposites containing 6FBPA-modified silica exhibited more uniformity than those of the nanocomposites containing BISAF-modified silica. The dielectric constants of the polyimide were considerably reduced by the incorporation of pristine silica or 6FBPA-modified silica but not BISAF-modified silica. The addition of a modifier with higher fluorine contents did not ensure a lower dielectric constant. The uniformity of the silica distribution, manipulated by the reactivity of the modifier, played an important role in the reduction of the dielectric constant. Using 6FBPA-modified silica nanoparticles demonstrated an effective way of synthesizing low-dielectric-constant polyimide-silica nanocomposites. (c) 2007 Wiley Periodicals, Inc.