Dr. Tammy P. Chou Profile

Dr. Tammy P. Chou

at Univ of Washington

SPIE Involvement:

Author

Publications (6)

SPIE Journal Paper | 1 December 2008

Enhanced light-conversion efficiency of titanium-dioxide dye-sensitized solar cells with the addition of indium-tin-oxide and fluorine-tin-oxide nanoparticles in electrode films

Tammy Chou, Qifeng Zhang, Bryan Russo, Guozhong Cao

JNP, Vol. 2, Issue 01, 023511, (December 2008) https://doi.org/10.1117/12.10.1117/1.3053995

KEYWORDS: Nanoparticles, Transparent conductors, Adsorption, Electrodes, Solar cells, Chemistry, Dye sensitized solar cells, Resistance, Bioalcohols, Titanium dioxide

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Proceedings Article | 14 October 2004 Paper

Development of titania nanostructures for the exploration of electron transport in dye-sensitized solar cells

Tammy Chou, Glen Fryxell, Xiaohong Li, Guozhong Cao

Proceedings Volume 5510, (2004) https://doi.org/10.1117/12.563083

KEYWORDS: Electrodes, Nanoparticles, Solar cells, Electron transport, Particles, Dye sensitized solar cells, Nanostructures, Scanning electron microscopy, Resistance, Nanorods

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Dye-sensitized solar cells (DSSC) utilizing titania (TiO₂) nanomaterials in conjunction with a light-absorbing dye have been extensively explored for the last few decades. Earlier efforts to surpass the 10% overall light conversion efficiency of these devices emphasized the synthesis of dyes with enhanced light-absorbing capabilities, but slow progress in the increase in efficiency has directed attention to the exploration into the modification of the TiO₂ nanostructure. Up to this point, the most efficient electrodes in DSSC devices have consisted of 10 micron-thick mesoporous TiO₂ film with an interconnected network of 15-20nm particles. This type of structure has shown to impart a large enough surface area for efficient light absorption and charge formation, but the random distribution of nanometer-sized particles is thought to be the limiting factor for enhanced electron transport, hindering further progress in achieving higher efficiencies. Our research utilizes TiO₂ nanorods in an attempt to explore and compare the electron transport pathways associated with 1) a random distribution of nanoparticles and 2) a straightforward arrangement of nanorods within the TiO₂ nanostructure. It is assumed that a more ordered structure of nanorods would minimize inefficient electron percolation pathways and improve ion diffusion at the TiO₂-dye-electrolyte interface by eliminating the randomization of the particle network, by increasing contact points for good electrical connection, and by decreasing small necking points that have shown to develop between adjacently-bound particles in the current TiO₂ nanoparticle structure after sintering. The current-voltage (I-V) behavior of three solar cell electrode structures consisting of (1) TiO₂ nanoparticle film, (2) TiO₂ nanoparticle-nanorod film, and (3) TiO₂ nanorod film were compared and analyzed to determine whether the nanorod structure provided a more efficient pathway for effective electron conduction. SEM analysis was also done to examine the structural alignment and morphology of each TiO₂ electrode.

Proceedings Article | 24 November 2003 Paper

Optically transparent superhydrophobic silica-based coatings

Mary Shang, Ying Wang, Steven Limmer, Tammy Chou, Guozhong Cao

Proceedings Volume 5224, (2003) https://doi.org/10.1117/12.524191

KEYWORDS: Optical coatings, Transmittance, Surface roughness, Silica, Chemistry, Atomic force microscopy, Silicon, Sol-gels, Solids, Glasses

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Proceedings Article | 24 November 2003 Paper

Ordered dye-functionalized TiO2 nanostructures for photoelectrochemical applications

Tammy Chou, Steven Limmer, Guozhong Cao

Proceedings Volume 5224, (2003) https://doi.org/10.1117/12.506074

KEYWORDS: Solar cells, Electrodes, Electrons, Nanostructures, Adsorption, Particles, Dye sensitized solar cells, Liquids, Photovoltaics, Nanorods

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Proceedings Article | 4 November 2002 Paper

Formation and optical properties of cylindrical gold nanoshells on silica and titania nanorods

Steven Limmer, Tammy Chou, Guozhong Cao

Proceedings Volume 4809, (2002) https://doi.org/10.1117/12.451624

KEYWORDS: Gold, Absorbance, Optical properties, Particles, Silica, Oxides, Sol-gels, Electrodes, Spherical lenses, Nanorods

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Proceedings Article | 4 November 2002 Paper

Functionalized, hierarchically structured mesoporous silica by sol electrophoresis and self-assembly

Tammy Chou, Steven Limmer, Guozhong Cao

Proceedings Volume 4809, (2002) https://doi.org/10.1117/12.451652

KEYWORDS: Silica, Ions, Lead, Chromophores, Molecules, Molecular self-assembly, Absorption, Glasses, Silicon, Nanorods

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Dye-functionalized mesoporous silica has gained considerable attention for use in optical applications. Much interest into the tunable functionality of these small-scale optical materials has been the focus for possible use in lasers, light filters, sensors, solar cells, and photocatalysis. Extensive exploration into functionalizing mesoporous silica has been made using sol-gel methods for incorporating polymeric dyes within the pore channels of the silica network to modify optical properties. However, research so far has been focused on functionalization of mesoporous silica powders or films on dense substrates, limiting applications in practice because of the difficult accessibility of mesopores. In this paper, we studied the development of hierarchically-structured mesoporous silica with chromophore dye molecules covalently linked within the channel walls of pores for the selective adsorption and detection of specific ions and chemical compounds. Hierarchically-structured, unidirectionally-aligned mesoporous silica was synthesized within the pores of polycarbonate membranes by surfactant-assisted sol electrophoretic deposition. After the removal of surfactants from the mesopores, the inner surface of the mesopores was functionalized with silane-containing chromophore molecules through self-assembly. Full coverage of these dye molecules on the surface of the mesopores was anticipated due to the fact that these reactant chromophore molecules, in solution, migrate through the pores. The organic chromophore dye molecules, assembled onto the surface of the mesopores, would have the amino groups exposed to the surface. These groups would have the capability to selectively interact with ions or chemical compounds in solution, for instance lead ions in water. Hence, the absorption spectrum of the chromophore dye molecules attached to the mesopores of silica was altered after exposure to lead ions in solution. In addition, the ion concentration in solution also differed. Such functionalized, hierarchically-structured mesoporous silica would have applications such as membranes for removal of, and sensors for, detecting trace amounts of ions and chemical compounds in water and air.

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