Miqin Zhang

Qifeng 'Jeff' Zhang

  • Research Assistant Professor
Office: 335 Roberts Hall
Phone: (206) 616-0918
Fax:(206) 543-3100
Email: qfzhang@uw.edu
Web: Nano Materials and Electronics Research Group

Education

Ph.D.   Peking University, 2001
B. S.    Beijing Institute of Technology, 1995

 

Research Interests

The relatively new field of nanoscience has rapidly evolved over the past two decades. Nanoscience entails the study of atomic and molecular scale phenomena and generally involves structures with a size between one to several hundred nanometers in at least one dimension. The feature of a nano-scale structure is that its geometrical size is smaller than the mean free path of electrons in the material. As such, nanomaterials usually exhibit very different properties in electronics and photonics when compared to bulk materials; this is known as the quantum confinement effect. In addition, nano-scale dimensions may result in a material with an extremely large specific surface area. This in turn leads to the use of nanomaterials in a wide range of applications in the fields of photovoltaics, photocatalysis, and chemical sensors. Accompanying the development of nanoscience is an increasing requirement for novel material fabrication techniques.

 

These techniques allow for the creation of such nanostructures as nanoparticles, nanowires/nanotubes, and nano-thin films so as to satisfy a specific application.
Our current research focuses on the synthesis of nanomaterials and the application of nanomaterials in electronic and optoelectronic devices such as dye-sensitized solar cells (DSCs). One of quite exciting results received recently is a use of a nanostructure of aggregates consisting of ZnO nanoparticles leading to an almost two-fold enhancement in the overall conversion efficiency of DSCs. This is attributed to light scattering generated by the aggregates, by means of which the traveling distance of light within the photoelectrode film may be significantly extended and the optical absorption of the photoelectrode film is therefore enhanced, making a contribution to the solar cell with an improvement in the overall conversion efficiency. (see University of Washington News: Popcorn-ball design doubles efficiency of dye-sensitized solar cells.) A further investigation which is ongoing with TiO2 material is anticipated to achieve a breakthrough in the ~11% conversion efficiencies of DSCs to date.

 

Besides dye-sensitized solar cells, many other types of photovoltaic devices built on nano-structured materials are also in our interests. Initial experimental study is planned to carry out on 1) organic/inorganic hybrid solar cells in which nanostructures may be employed for an increase in the active area of the photoelectrode and generate optical localization so as to enhance the light absorption as well as the power conversion efficiency of the cells, and 2) compound semiconductor thin film solar cells, which are proud to have high efficiencies, ~18%, and relatively low cost of the materials and manufacturing; our efforts are aimed at the synthesis and doping of compound semiconductors (for example, copper indium gallium selenide (CIGS), cadmium sulfide, and cadmium telluride) in a sol-gel process and developing to nanostructures for any improvements in the light harvesting and/or charge transport of the solar cells.

 

Selected Recent Publications

  • [1]     Q. F. Zhang and G. Z. Cao, "Nanostructured photoelectrodes for dye-sensitized solar cells," Nano Today, vol. 6, pp. 91-109, 2011.

    [2]     D. M. Yu, C. G. Chen, S. H. Xie, Y. Y. Liu, K. Park, X. Y. Zhou, Q. F. Zhang, J. Y. Li, and G. Z. Cao, "Mesoporous vanadium pentoxide nanofibers with significantly enhanced Li-ion storage properties by electrospinning," Energy & Environmental Science, vol. 4, pp. 858-861, Mar 2011.
  • [3]     J. T. Xi, Q. F. Zhang, K. Park, Y. M. Sun, and G. Z. Cao, "Enhanced power conversion efficiency in dye-sensitized solar cells with TiO2 aggregates/nanocrystallites mixed photoelectrodes," Electrochimica Acta, vol. 56, pp. 1960-1966, Feb 2011.
  • [4]     K. Park, Q. F. Zhang, B. B. Garcia, and G. Z. Cao, "Effect of Annealing Temperature on TiO2-ZnO Core-Shell Aggregate Photoelectrodes of Dye-Sensitized Solar Cells," Journal of Physical Chemistry C, vol. 115, pp. 4927-4934, Mar 2011.
  • [5]     Y. Y. Liu, D. W. Liu, Q. F. Zhang, D. M. Yu, J. Liu, and G. Z. Cao, "Lithium iron phosphate/carbon nanocomposite film cathodes for high energy lithium ion batteries," Electrochimica Acta, vol. 56, pp. 2559-2565, Feb 2011.
  • [6]     Q. F. Zhang, K. Park, and G. Z. Cao, "A New Microstructured DSC Photoelectrode for Potential High Power Conversion Efficiency," Journal of the Chinese Chemical Society, vol. 57, pp. 1119-1126, Oct 2010.
  • [7]     Q. F. Zhang, C. S. Dandeneau, K. Park, D. W. Liu, X. Y. Zhou, Y. H. Jeong, and G. Z. Cao, "Light scattering with oxide nanocrystallite aggregates for dye-sensitized solar cell application," Journal of Nanophotonics, vol. 4, p. 041540, May 2010.
  • [8]     Q. F. Zhang, C. S. Dandeneau, S. Candelaria, D. W. Liu, B. B. Garcia, X. Y. Zhou, Y. H. Jeong, and G. Z. Cao, "Effects of Lithium Ions on Dye-Sensitized ZnO Aggregate Solar Cells," Chemistry of Materials, vol. 22, pp. 2427-2433, Apr 2010.
  • [9]     D. M. Yu, S. T. Zhang, D. W. Liu, X. Y. Zhou, S. H. Xie, Q. F. Zhang, Y. Y. Liu, and G. Z. Cao, "Effect of manganese doping on Li-ion intercalation properties of V2O5 films," Journal of Materials Chemistry, vol. 20, pp. 10841-10846, 2010.
  • [10]   S. Yodyingyong, X. Y. Zhou, Q. F. Zhang, D. Triampo, J. T. Xi, K. Park, B. Limketkai, and G. Z. Cao, "Enhanced Photovoltaic Performance of Nanostructured Hybrid Solar Cell Using Highly Oriented TiO2 Nanotubes," Journal of Physical Chemistry C, vol. 114, pp. 21851-21855, Dec 2010.
  • [11]   S. Yodyingyong, Q. F. Zhang, K. Park, C. S. Dandeneau, X. Y. Zhou, D. Triampo, and G. Z. Cao, "ZnO nanoparticles and nanowire array hybrid photoanodes for dye-sensitized solar cells," Applied Physics Letters, vol. 96, p. 073115, Feb 2010.
  • [12]   K. Park, Q. F. Zhang, B. B. Garcia, X. Y. Zhou, Y. H. Jeong, and G. Z. Cao, "Effect of an Ultrathin TiO2 Layer Coated on Submicrometer-Sized ZnO Nanocrystallite Aggregates by Atomic Layer Deposition on the Performance of Dye-Sensitized Solar Cells," Advanced Materials, vol. 22, pp. 2329-2332, Jun 2010.
  • [13]   T. S. Deng, J. Y. Zhang, K. T. Zhu, Q. F. Zhang, and J. L. Wu, "Highly monodisperse vinyl functionalized silica spheres and their self-assembled three-dimensional colloidal photonic crystals," Colloids and Surfaces a-Physicochemical and Engineering Aspects, vol. 356, pp. 104-111, Mar 2010.
  • [14]   T. S. Deng, J. Y. Zhang, K. T. Zhu, Q. F. Zhang, and J. L. Wu, "Controlled tuning of the stop band of colloidal photonic crystals by thermal annealing," Optical Materials, vol. 32, pp. 946-949, Jul 2010.
  • [15]   T. S. Deng, J. Y. Zhang, K. T. Zhu, Q. F. Zhang, and J. L. Wu, "Improving the optical properties of vinyl-functionalized silica colloidal crystals by thermal annealing," Journal of the Ceramic Society of Japan, vol. 118, pp. 862-866, Oct 2010.
  • [16]   Q. F. Zhang, C. S. Dandeneau, X. Y. Zhou, and G. Z. Cao, "ZnO Nanostructures for Dye-Sensitized Solar Cells," Advanced Materials, vol. 21, pp. 4087-4108, Nov 2009.
  • [17]   J. Y. Zhang, Q. F. Zhang, T. S. Deng, and J. L. Wu, "Electrically driven ultraviolet lasing behavior from phosphorus-doped p-ZnO nanonail array/n-Si heterojunction," Applied Physics Letters, vol. 95, p. 211107, Nov 2009.
  • [18]   J. Y. Zhang, T. S. Deng, X. Shen, K. T. Zhu, Q. F. Zhang, and J. L. Wu, "Electrical and optical properties of single As-doped ZnO nanowire field effect transistors," Acta Physica Sinica, vol. 58, pp. 4156-4161, Jun 2009.
  • [19]   M. H. Sun, Q. F. Zhang, H. Sun, J. Y. Zhang, and J. L. Wu, "Enhanced ultraviolet electroluminescence from p-Si/n-ZnO nanorod array heterojunction," Journal of Vacuum Science & Technology B, vol. 27, pp. 618-621, Mar-Apr 2009.
  • [20]   S. Sepehri, B. B. Garcia, Q. F. Zhang, and G. Z. Cao, "Enhanced electrochemical and structural properties of carbon cryogels by surface chemistry alteration with boron and nitrogen," Carbon, vol. 47, pp. 1436-1443, May 2009.
  • [21]   D. W. Liu, Y. H. Zhang, P. Xiao, B. B. Garcia, Q. F. Zhang, X. Y. Zhou, Y. H. Jeong, and G. Z. Cao, "TiO2 nanotube arrays annealed in CO exhibiting high performance for lithium ion intercalation," Electrochimica Acta, vol. 54, pp. 6816-6820, Nov 2009.
  • [22]   D. W. Liu, Y. Y. Liu, B. B. Garcia, Q. F. Zhang, A. Q. Pan, Y. H. Jeong, and G. Z. Cao, "V2O5 xerogel electrodes with much enhanced lithium-ion intercalation properties with N2 annealing," Journal of Materials Chemistry, vol. 19, pp. 8789-8795, 2009.
  • [23]   D. W. Liu, B. B. Garcia, Q. F. Zhang, Q. Guo, Y. H. Zhang, S. Sepehri, and G. Z. Cao, "Mesoporous Hydrous Manganese Dioxide Nanowall Arrays with Large Lithium Ion Energy Storage Capacities," Advanced Functional Materials, vol. 19, pp. 1015-1023, Apr 2009.
  • [24]   T. S. Deng, Q. F. Zhang, J. Y. Zhang, X. Shen, K. T. Zhu, and J. L. Wu, "One-step synthesis of highly monodisperse hybrid silica spheres in aqueous solution," Journal of Colloid and Interface Science, vol. 329, pp. 292-299, Jan 2009.
  • [25]   W. J. Zhang, J. Y. Zhang, P. J. Li, X. Shen, Q. F. Zhang, and J. L. Wu, "The effects of contacts and ambipolar electrical transport in nitrogen doped multiwall carbon nanotubes," Nanotechnology, vol. 19, p. 085202, Feb 2008.
  • [26]   Q. F. Zhang, T. R. Chou, B. Russo, S. A. Jenekhe, and G. Z. Cao, "Aggregation of ZnO nanocrystallites for high conversion efficiency in dye-sensitized solar cells," Angewandte Chemie-International Edition, vol. 47, pp. 2402-2406, 2008.
  • [27]   Q. F. Zhang, T. P. Chou, B. Russo, S. A. Jenekhe, and G. Cao, "Polydisperse aggregates of ZnO nanocrystallites: A method for energy-conversion-efficiency enhancement in dye-sensitized solar cells," Advanced Functional Materials, vol. 18, pp. 1654-1660, Jun 2008.
  • [28]   J. Y. Zhang, P. J. Li, H. Sun, X. Shen, T. S. Deng, K. T. Zhu, Q. F. Zhang, and J. L. Wu, "Ultraviolet electroluminescence from controlled arsenic-doped ZnO nanowire homojunctions," Applied Physics Letters, vol. 93, p. 021116, Jul 2008.
  • [29]   Y. X. Wang, Q. F. Zhang, H. Sun, Y. L. Chang, and J. L. Wu, "Fabrication of ZnO nanowire-based diodes and their light-emitting properties," Acta Physica Sinica, vol. 57, pp. 1141-1144, Feb 2008.
  • [30]   D. W. Liu, Q. F. Zhang, P. Xiao, B. B. Garcia, Q. Guo, R. Champion, and G. Z. Cao, "Hydrous manganese dioxide nanowall arrays growth and their Li+ ions intercalation electrochemical properties," Chemistry of Materials, vol. 20, pp. 1376-1380, Feb 2008.
  • [31]   D. W. Liu, P. Xiao, Y. H. Zhang, B. B. Garcia, Q. F. Zhang, Q. Guo, R. Champion, and G. Z. Cao, "TiO2 nanotube arrays annealed in N2 for efficient lithium-ion intercalation," Journal of Physical Chemistry C, vol. 112, pp. 11175-11180, Jul 2008.
  • [32]   B. B. Garcia, A. M. Feaver, Q. F. Zhang, R. D. Champion, G. Z. Cao, T. T. Fister, K. P. Nagle, and G. T. Seidler, "Effect of pore morphology on the electrochemical properties of electric double layer carbon cryogel supercapacitors," Journal of Applied Physics, vol. 104, p. 014305, Jul 2008.
  • [33]   T. P. Chou, Q. F. Zhang, B. Russo, and G. Z. Cao, "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," Journal of Nanophotonics, vol. 2, p. 023511, 2008.
  • [34]   W. J. Zhang, Q. F. Zhang, Y. Chai, X. Shen, and J. L. Wu, "Gate voltage dependent characteristics of p-n diodes and bipolar transistors based on multiwall CNx/carbon nanotube intramolecular junctions," Nanotechnology, vol. 18, p. 395205, Oct 2007.
  • [35]   Q. Wang, Q. F. Zhang, H. Sun, J. Y. Zhang, T. S. Deng, and J. L. Wu, "Growth and optical characteristics of ZnO photonic crystals," Acta Physico-Chimica Sinica, vol. 23, pp. 1667-1670, Nov 2007.
  • [36]   M. H. Sun, Q. F. Zhang, and J. L. Wu, "Electrical and electroluminescence properties of As-doped p-type ZnO nanorod arrays," Journal of Physics D-Applied Physics, vol. 40, pp. 3798-3802, Jun 2007.
  • [37]   H. Sun, Q. F. Zhang, and J. L. Wu, "Ultraviolet light emitting diode based on ZnO nanowires," Acta Physica Sinica, vol. 56, pp. 3479-3482, Jun 2007.
  • [38]   P. H. Li, W. J. Zhang, Q. F. Zhang, and J. L. Wu, "Nanoelectronic logic circuits with carbon nanotube transistors," Acta Physica Sinica, vol. 56, pp. 1054-1060, Feb 2007.
  • [39]   T. P. Chou, Q. F. Zhang, B. Russo, G. E. Fryxell, and G. Z. Cao, "Titania particle size effect on the overall performance of dye-sensitized solar cells," Journal of Physical Chemistry C, vol. 111, pp. 6296-6302, May 2007.
  • [40]   T. P. Chou, Q. F. Zhang, G. E. Fryxell, and G. Z. Cao, "Hierarchically structured ZnO film for dye-sensitized solar cells with enhanced energy conversion efficiency," Advanced Materials, vol. 19, pp. 2588-2592, Sep 2007.
  • [41]   T. P. Chou, Q. F. Zhang, and G. Z. Cao, "Effects of dye loading conditions on the energy conversion efficiency of ZnO and TiO2 dye-sensitized solar cells," Journal of Physical Chemistry C, vol. 111, pp. 18804-18811, Dec 2007.
  • [42]   Y. L. Chang, Q. F. Zhang, H. Sun, and J. L. Wu, "Development and behavior study of a ZnO nanowire-based electroluminescence device with double insulating-layer structure," Acta Physica Sinica, vol. 56, pp. 2399-2404, Apr 2007.
  • [43]   W. J. Zhang, Q. F. Zhang, and J. L. Wu, "Time-related conversion of the carbon nanotube field effect transistor," Applied Physics Letters, vol. 89, p. 233507, Dec 2006.
  • [44]   H. Sun, Q. F. Zhang, and J. L. Wu, "Electroluminescence from ZnO nanorods with an n-ZnO/p-Si heterojunction structure," Nanotechnology, vol. 17, pp. 2271-2274, May 2006.
  • [45]   G. H. Pan, Q. F. Zhang, J. Y. Zhang, and J. L. Wu, "Luminescence properties of as-doping ZnO nanowires," Acta Physico-Chimica Sinica, vol. 22, pp. 1431-1434, Nov 2006.
  • [46]   P. J. Li, W. J. Zhang, Q. F. Zhang, and J. L. Wu, "The influence of contact metal in carbon nanotube transistor," Acta Physica Sinica, vol. 55, pp. 5460-5465, Oct 2006.
  • [47]   Y. Chai, Q. F. Zhang, and J. L. Wu, "A simple way to CNx/carbon nanotube intramolecular junctions and branches," Carbon, vol. 44, pp. 687-691, Apr 2006.

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UW Department of Materials Science & Engineering

phone: (206) 543-2600
fax: (206) 543-3100

mse@u.washington.edu