Prof. Guozhong Cao Profile

Prof. Guozhong Cao

Boeing-Steiner Professor of Materials Sci Engg at Univ of Washington

SPIE Involvement:

Author | Instructor

SPIE Journal Paper | 7 August 2012 Open Access

Hollow hemispherical titanium dioxide aggregates fabricated by coaxial electrospray for dye-sensitized solar cell application

Junting Xi, Qifeng Zhang, Daniel Myers, Guozhong Cao, Yueming Sun

JNP, Vol. 6, Issue 01, 063519, (August 2012) https://doi.org/10.1117/12.10.1117/1.JNP.6.063519

KEYWORDS: Dye sensitized solar cells, Light scattering, Adsorption, Nanoparticles, Liquids, Scanning electron microscopy, Solar cells, Absorption, Diffuse reflectance spectroscopy, Titanium dioxide

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Proceedings Article | 26 May 2011 Paper

Strong room-temperature chemiresistive effect of TiO2 nanowires to nitro-aromatic compounds

Danling Wang, Antao Chen, Qifeng Zhang, Guozhong Cao

Proceedings Volume 8024, 80240W (2011) https://doi.org/10.1117/12.885065

KEYWORDS: Resistance, Thin films, Explosives, Molecules, Sensors, Metals, Nanostructuring, Semiconductors, Nanowires, Titanium dioxide

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Proceedings Article | 14 April 2011 Paper

Development of sol-gel derived lead zirconate titanate (PZT) thin films with a nonporous Pt/Ti bottom electrode

Qing Guo, G. Z. Cao, I. Y. Shen

Proceedings Volume 7981, 79812U (2011) https://doi.org/10.1117/12.881460

KEYWORDS: Electrodes, Ferroelectric materials, Thin films, Platinum, Annealing, Capacitance, Semiconducting wafers, Silicon, Oscilloscopes, Sol-gels

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SPIE Journal Paper | 1 May 2010

Light scattering with oxide nanocrystallite aggregates for dye-sensitized solar cell application

Qifeng Zhang, Christopher Dandeneau, Kwangsuk Park, Dawei Liu, Xiaoyuan Zhou, Yoon-Ha Jeong, Guozhong Cao

JNP, Vol. 4, Issue 01, 041540, (May 2010) https://doi.org/10.1117/12.10.1117/1.3436678

KEYWORDS: Zinc oxide, Light scattering, Absorption, Dye sensitized solar cells, Solar cells, Lithium, Oxides, Ions, Scattering, Scanning electron microscopy

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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 | 18 November 2005 Paper

Processing and optical properties of sol-gel derived nanostructured CdWO₄ films

H. Shang, Y. Wang, M. Bliss, G. Cao

Proceedings Volume 6008, 60081B (2005) https://doi.org/10.1117/12.629737

KEYWORDS: Tungsten, Crystals, Sol-gels, Cadmium, Luminescence, Particles, Transparency, Optical properties, Oxides, Hydrogen

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Proceedings Article | 29 December 2004 Paper

Template-based growth of nanorod arrays by solution methods

Guozhong Cao

Proceedings Volume 5593, (2004) https://doi.org/10.1117/12.572019

KEYWORDS: Oxides, Crystals, Particles, Sol-gels, Vanadium, Photomicroscopy, Ferroelectric materials, Electrodes, Nanoparticles, Nanorods

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Proceedings Article | 14 October 2004 Paper

Synthesis and electrochromic property of single-crystalline V2O5 nanorod arrays by template-based deposition

Katsunori Takahashi, Steven Limmer, Ying Wang, Guozhong Cao

Proceedings Volume 5510, (2004) https://doi.org/10.1117/12.563104

KEYWORDS: Vanadium, Crystals, Sol-gels, Transmittance, Electrodes, Lithium, Oxides, Diffraction, Diffusion, Nanorods

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Proceedings Article | 14 October 2004 Paper

Doping effects on microstructure and scintillation properties of cadmium tungstate films

Huamei Shang, Ying Wang, Brian Milbrath, Mary Bliss, Guozhong Cao

Proceedings Volume 5510, (2004) https://doi.org/10.1117/12.563220

KEYWORDS: Ions, Doping, Luminescence, Cadmium, Lithium, Bismuth, Crystals, Tungsten, Sol-gels, Transmittance

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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

Electrochromic and transparent conducting oxide nanorods

Steven Limmer, Katsunori Takahashi, Guozhong Cao

Proceedings Volume 5224, (2003) https://doi.org/10.1117/12.505864

KEYWORDS: Absorbance, Niobium, Oxides, Vanadium, Electrodes, Transparent conducting oxide, Glasses, Tin, Scanning electron microscopy, Nanorods

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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 | 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

Template-based growth of V2O5 nanorods by electrodeposition

Katsunori Takahashi, Steven Limmer, Guozhong Cao

Proceedings Volume 5224, (2003) https://doi.org/10.1117/12.507364

KEYWORDS: Vanadium, Crystals, Electrodes, Oxides, Nanoparticles, Absorption, Transmission electron microscopy, Ions, Absorbance, Nanorods

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Proceedings Article | 14 July 2003 Paper

Grassland desertification monitoring by remote sensing and GIS in the upper reaches of the Yellow River, northeast Qinghai-Xizang Plateau

Yongnian Zeng, Zhaodong Feng, Guangchao Cao, Weguo Wang

Proceedings Volume 4890, (2003) https://doi.org/10.1117/12.487568

KEYWORDS: Geographic information systems, Climatology, Remote sensing, Ecosystems, Climate change, Landsat, Vegetation, Data modeling, Analytical research, Earth observing sensors

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Proceedings Article | 4 November 2002 Paper

Synthesis of CdWO4 films via sol-gel processing

Kirk Lennstrom, Steven Limmer, Guozhong Cao

Proceedings Volume 4809, (2002) https://doi.org/10.1117/12.451646

KEYWORDS: Crystals, Cadmium, Sol-gels, Luminescence, Particles, Thin films, Tungsten, Scanning electron microscopy, Quartz, X-ray diffraction

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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.

Proceedings Article | 15 July 2002 Paper

Feasibility study of PZT thin-film sensors and actuators for smart microstructures and MEMS devices

Yi-Chu Hsu, I. Shen, G. Cao

Proceedings Volume 4701, (2002) https://doi.org/10.1117/12.474676

KEYWORDS: Ferroelectric materials, Thin films, Actuators, Sensors, Microelectromechanical systems, Silicon, Laser Doppler velocimetry, Thin film devices, Silicon films, Sol-gels

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Showing 5 of 19 publications

SPIE Conference Volume | 14 October 2004

Nanophotonic Materials

SPIE Conference Volume | 24 November 2003

Nanomaterials and Their Optical Applications

SPIE Conference Volume | 4 November 2002

Nanoscale Optics and Applications

Conference Committee Involvement (3)

Nanophotonic Materials

2 August 2004 | Denver, Colorado, United States

Nanomaterials and Their Optical Applications

5 August 2003 | San Diego, California, United States

Nanoscale Optics and Applications

8 July 2002 | Seattle, WA, United States

Course Instructor

SC496: Fabrication and Processing of Nanostructures

The objective of this course is to provide attendees with a good understanding of the fundamentals and comprehensive knowledge in the field of nanotechnology, with the emphasis on the fabrication, characterization, properties and applications of nanomaterials. More specifically, this course will cover (1) basic principles (including thermodynamics, kinetics and mass transfer) related to fabrication of nanomaterials, (2) a comprehensive review of the established techniques and methods for the synthesis and characterization of nanomaterials and nanostructures, (3) unique physical properties of nanomaterials, and (4) various applications of nanostructures and nanomaterials including, but not limited to, in clean energy such as solar cells, lithium ion batteries, supercapacitors, and thermoelectrics.

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