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Department of Chemistry and Applied Biological Sciences

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RESEARCH

EDUCATION

PUBLICATION

FACILITIES

OPENINGS

SPONSORS



Zhengtao Zhu


Associate Professor
Department of Chemistry and Applied Biological Sciences
South Dakota School of Mines and Technology
501 E. Saint Joseph Street
Rapid City, SD 57701
Phone: 605-394-2447
Email: Zhengtao.Zhu@sdsmt.edu


  • Research Interests: Materials science of electronically active conjugated polymer and nanomaterial composites, with the goal to elucidate the unique optical and charge transport properties of these materials at the nanometer scale and to explore the applications of these materials in flexible electronics and sensors.
  • Education:
  • Experience:

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Research

We are interested in the materials science of electronically active conjugated polymer and nanomaterial composites, with the goals to elucidate the unique optical and charge transport properties of these materials at the nanometer scale and to explore the applications of these materials in flexible electronics and sensors. For example, hybrid photovoltaic cells that consist of bulk heterojunction of conjugated polymer as the electron donor and semiconducting oxide nanoparticle as the electron acceptor have been demonstrated. In these hybrid devices, the principle of device operation includes four key steps: photoexcitation and electron-hole exciton dissociation (step 1), ultrafast charge transfer (step 2), charge transport (step 3), charge injection at the electrode (step 4).  These four steps determine the energy conversion efficiency, and any factor that is related to these processes may affect the device performance. To improve the optoelectronic devices based on the hybrid material, it is critical for us to understand the formation of bulk heterojunctions, and the factors related to photophysics and charge transport properties of conjugated polymer/oxide nanoparticle blends.

1.      Photophysics of conjugated polymer/nanoparticles nanfibers. We are interested in understanding the effects of polymer chain conformation, conjugated polymer/ZnO interaction, and morphology on the optical and electronic properties of the nanofibers. Nanofibers of MEH-PPV/ZnO are prepared by the electrospinning process. Fluorescent measurement combined with near-field scanning optical microscope is used to reveal the photophysics of the nanofibers at local nanometer scale.

2.      Charge transport in the nanocomposites Field-effect transistors of polythiophene/ZnO nanoparticles will be fabricated and characterized, and the charge carrier mobilities and the contact resistance will be extracted in order to understand the charge transport properties. The effects of film composition and morphology on the charge transport will be analyzed by correlating the charge transport parameters with the concentration of the ZnO nanoparticles and the SEM/TEM results of the thin films. Furthermore, the temperature dependence of the field-effect mobility will be investigated to understand the charge transport mechanism.

3.      Flexible chemical sensors The effect of different gases and organic vapors on the charge transport of hybrid materials based on polythiophene and ZnO nanoparticles (NPs) will be explored. The goals of the project are to understand the interactions between the conducting polymers and nanoparticles and to utilize these interactions between the two components for high performance chemical sensors. The salient features of the proposed sensor platform include high sensitivity and selectivity, light weighted, and flexibility on rugged substrate.

 

research

 

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Education

Courses taught:

Undergraduate courses: General Chemistry I (Chem 112), Chemistry Survey (Chem 106), Descriptive Inorganic Chemistry (Chem252), Inorganic Chemistry (Chem 452/552), Inorganic Chemistry Lab (Chem 452L), Undergraduate Seminar (Chem 290/490).

Graduate courses: Chemistry of Materials (MES 604), Nanochemistry (Nano717), Polymeric Nanomaterials (Nano715).

Outreach:

    • STEPS Summer Camp: In this summer (2009), I have been working with Science Technology Engineering Preview Summer Camp (STEPS) to introduce the concept of nanotechnology to middle and high school kids through a 10 minutes fun talk and a hand-on experiment of gold nanoparticle synthesis.

outreach
High school girls work on gold nanoparticle synthesis
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Publications

  1. Wang, X.; Guo, L.; Xia, P. F.; Zheng, F.; Wong, M. S.; Zhu, Z.-T. Effects of surface modification on dye-sensitized solar cell based on an organic dye with naphtho [2, 1-b: 3, 4-b] dithiophene as the conjugated linker ACS Appl Mater. Interfaces, in press, http://dx.doi.org/10.1021/am404984g.
  2. Lai, C.; Zhou, Z.; Zhang, L.; Wang, X.; Zhou, Q.; Zhao, Y.; Wang, Y.; Wu, X.-F. Wu;* Zhu, Z.-T.; Fong, H.* Free-standing and mechanically flexible mats consisting of electrospun carbon nanofibers made from a natural product of alkali lignin as binder-free electrodes for high-performance supercapacitors J. Power Sources, 2014, 247, 134.
  3. Wang, X.; Guo, L.; Xia, P. F.; Zheng, F.; Wong, M. S.;* Zhu, Z.-T.* Dye-sensitized solar cells based on organic dyes with naphtho [2, 1-b: 3, 4-b] dithiophene as the conjugated linker J. Mater. Chem. A, 2013 42, 13328.
  4. Wang, X.; He, G.; Fong, H.;* Zhu, Z.-T.* Electron transport and recombination in photoanode of electrospun TiO2 nanotubes for dye-sensitized solar cells J Phys Chem C 2013, 117, 1641.
  5. He, G.; Wang, X.; Xi, M.; Zheng, F.; Zhu, Z.-T.;* Fong, H.* Fabrication and evaluation of dye-sensitized solar cells with photoanodes based on electrospun TiO2 nanotubes Mater Lett 2013, 106, 115.
  6. Bao, Y.; Lai, C.; Zhu, Z.-T.; Fong, H.;* Jiang, C.* SERS-active silver nanoparticles on electrospun nanofibers facilitated via oxygen plasma etching, RSC Adv 2013, 3, 8998.
  7. He, G.; Cai, Y.; Zhao, Y.; Wang, X.; Lai, C.; Xi, M.; Zhu, Z.-T.;* Fong, H.* Electrospun anatase phase TiO2 nanofibers with different morphological structures and specific surface areas J Colloid Interface Sci 2013, 398, 103.
  8. Lai, C.; Wang, X.; Zhao, Y.; Fong, H.;* Zhu, Z.-T.* Effects of humidity on the ultraviolet nanosensors of aligned electrospun ZnO nanofibers RSC Adv 2013, 3, 6640.
  9. Zhao, Y.; Wang, X.; Lai, C.; He, G.; Zhang, L. F.; Fong, H.;* Zhu, Z.-T.* Deposition of Pd nanoparticles on electrospun carbon nanofibers by the supercritical CO2 method for hydrogen sensors RSC Adv 2012, 2, 10195.
  10. Zhang, L. F.; Wang, X.; Zhao, Y.; Zhu, Z.-T.;* Fong, H.* Electrospun carbon nano-felt surface attached with Pd nanoparticles for hydrogen sensing application Mater Lett 2012, 68, 133.
  11. Hedin, N.; Sobolev, V.;* Zhang, L. F.; Zhu, Z.-T.; Fong, H.* Electrical properties of electrospun carbon nanofibers J Mater Sci 2011, 46, 6453.
  12. Wang, X.; Karanjit,S.; Zhang, L.; Joshi, P.; Fong, H.; Qiao, Q.;* Zhu, Z.-T.* Transient photo-current and photo-voltage studies on charge transport in dye sensitized solar cells made from the composites of TiO2 nanofibers and nanoparticles Appl Phys Lett 2011, 98, 082114.

13.  Yin, K.; Zhang, L.; Lai, C.; Zhong, L.; Smith, S.; Fong, H.;* Zhu, Z.-T.* Photoluminescence anisotropy of uni-axially aligned electrospun conjugated polymer nanofibers of MEH-PPV and P3HT J. Mater. Chem. 2011, 21, 444-448.

  1. Jetson R; Yin, K.; Donovana, K.; Zhu, Z.-T.* Effects of surface modification on the fluorescence properties of conjugated polymer/ZnO nanocomposites Mater. Chem. Phys. 2010, 124, 417-421.
  2. Joshi, P.; Zhang, L.; Davoux, D.; Zhu, Z.-T.; Galipeau, D.; Fong, H.;* Qiao, Q.* Composite of TiO2 nanofibers and nanoparticles for dye sensitized solar cells with significantly improved efficiency Energy Environ. Sci. 2010, 3, 1507-1510.
  3. Yin, K.; Zhu, Z.-T.* "One-pot" synthesis, characterization, and NH3 sensing of Pd/PEDOT:PSS nanocomposite Synth Met 2010 160, 1115.
  4. Zhu, Z.-T.;* Zhang, L. F.; Howe, J. Y.; Liao, Y. L.; Speidel, J. T.; Smith, S.; Fong, H.* Aligned electrospun ZnO nanofibers for simple and sensitive ultraviolet nanosensors Chem Commun 2009 , 2568.
  5. Zhu, Z.;* Zhang, L.; Smith, S.; Fong, H.*; Sun, Y.; Gosztola, D. Fluorescence studies of electrospun MEH-PPV/PEO nanofibers Synth Met 2009 159, 1454.
  6. Ahn, J.-H.; Zhu, Z.; Park, S.-I.; Xiao, J.; Huang, Y.; Rogers, J. A.* Defect tolerance and nanomechanics in transistors that use semiconductor nanomaterials and ultrathin dielectrics Adv Funct Mater 2008 18, 2535.
  7. Liao, Y.; Zhang, L.; Gao, Y.; Zhu, Z.-T.;* Fong, H.* Preparation, characterization, and encapsulation/release studies of a composite nanofiber mat electrospun from an emulsion containing poly(lactic-co-glycolic acid) Polymer 2008 49, 5294.
  8. Ahn, J.-H.; Kim, H.-S.; Menard, E.; Lee, K. J.; Zhu, Z.; Kim, D.-H.; Nuzzo, R. G.; Rogers, J. A.* Bendable integrated circuits on plastic substrates by use of printed ribbons of single-crystalline silicon Appl Phys Lett 2007 90, 213501.
  9. Ahn, J.-H.; Kim, H.-S.; Lee, K.; Zhu, Z.; Menard, E.; Nuzzo, R.; Rogers, J.* High-speed mechanically flexible single-crystal silicon thin-film transistors on plastic substrates IEEE Electron Dev Lett 2006 27, 460.
  10. Cao, Q.; Hur, S.-H.; Zhu, Z.-T.; Sun, Y.; Wang, C.; Meitl, M.; Shim, M.; Rogers, J.* Highly bendable, transparent thin-film transistors that use carbon-nanotube-based conductors and semiconductors with elastomeric dielectrics Adv Mater 2006 18, 304.
  11. Cao, Q.; Zhu, Z.-T.; Lemaitre, M.; Xia, M.-G.; Shim, M.; Rogers, J.* Transparent flexible organic thin-film transistors that use printed single-walled carbon nanotube electrodes Appl Phys Lett 2006 88, 113511.
  12. Mack, S.; Meitl, M.; Baca, A.; Zhu, Z.-T.; Rogers, J.* Mechanically flexible thin-film transistors that use ultrathin ribbons of silicon derived from bulk wafers Appl Phys Lett 2006 88, 213101.
  13. Meitl, M.; Zhu, Z.-T.; Kumar, V.; Lee, K.; Feng, X.; Huang, Y.; Adesida, I.; Nuzzo, R.; Rogers, J.* Transfer printing by kinetic control of adhesion to an elastomeric stamp Nat Mater 2006 5, 33.
  14. Zhu, Z.-T.; Menard, E.; Hurley, K.; Nuzzo, R.; Rogers, J.* Spin on dopants for high-performance single-crystal silicon transistors on flexible plastic substrates Appl Phys Lett 2005 86, 133507.
  15. Zhu, Z.-T.; Mabeck, J.; Zhu, C.; Cady, N.; Batt, C.; Malliaras, G.* A simple poly(3,4-ethylene dioxythiophene)/poly(styrene sulfonic acid) transistor for glucose sensing at neutral pH Chem Commun 2004 10, 1556.
  16. Zhu, Z.-T.; Musfeldt, J.;* Kamars, K.; Adams, G.; Page, J.; Kashevarova, L.; Rakhmanina, A.; Davydov, V. Far-infrared vibrational properties of linear C60 polymers: A comparison between neutral and charged materials Phys Rev B 2003 67, 454091.
  17. Choi, J.;Zhu, Z.; Musfeldt, J.;* Ragghianti, G.; Mandrus, D.; Sales, B.; Thompson, J. Local symmetry breaking in K2V3O8 as studied by infrared spectroscopy Phys Rev B 2002 65, 541011.
  18. Musfeldt, J.;* Zhu, Z.; Teweldemedhin, Z.; Greenblatt, M. Layered tungsten bronzes: Tuning the optical properties by changing the layer thickness J Phys IV 2002 12, 361.
  19. Zhu, Z.-T.; Musfeldt, J.;* Koo, H.-J.; Whangbo, M.-H.; Teweldemedhin, Z.; Greenblatt, M. Dimensionality effects on the optical properties of (PO2)4(WO3)2m (m = 2, 4, 6, 7) Chem Mater 2002 14, 2607.
  20. Zhu, Z.-T.; Musfeldt, J.;* Kamars, K.; Adams, G.; Page, J.; Davydov, V.; Kashevarova, L.; Rakhmanina, A. Far-infrared vibrational properties of tetragonal C60 polymer Phys Rev B 2002 65, 854131.
  21. Zhu, Z.-T.; Musfeldt, J.;* Teweldemedhin, Z.; Greenblatt, M. Anisotropic ab-plane optical response of the charge-density-wave superconductor P4W14O50 Phys Rev B 2002 65, 2145191.
  22. Zhu, Z.-T.; Mason, J.; Dieckmann, R.; Malliaras, G.* Humidity sensors based on pentacene thin-film transistors Appl Phys Lett 2002 81, 4643.
  23. Olejniczak, I.; Jones, B.; Dong, J.; Pigos, J.; Zhu, Z.-T.; Garlach, A.; Musfeldt, J.;* Koo, H.-J.; Whangbo, M.-H.; Schlueter, J.; Ward, B.; Morales, E.; Kini, A.; Winter, R.; Mohtasham, J.; Gard, G. Optical studies of the β′′ -(ET)2 SF5RSO3 (R=CH2CF2, CHFCF2 and CHF) system: Chemical tuning of the counterion Synth Met 2001 120, 785.
  24. Pigos, J.; Jones, B.; Zhu, Z.-T.; Musfeldt, J.;* Homes, C.; Koo, H.-J.; Whangbo, M.-H.; Schlueter, J.; Ward, B.; Wang, H.; Geiser, U.; Mohtasham, J.; Winter, R.; Gard, G. Infrared and optical properties of β-(ET)2SF5CF2SO3: Evidence for a 45 k spin-Peierls transition Chem Mater 2001 13, 1326.
  25. Zhu, Z.-T.; Musfeldt, J.;* Teweldemedhin, Z.; Greenblatt, M. Vibrational properties of monophosphate tungsten bronzes (PO2)4(WO3)2m (m = 4, 6) Chem Mater 2001 13, 2940.
  26. Zhu, Z.; Musfeldt, J.;* Wang, Y.-J.; Negishi, H.; Inoue, M.; Sarrao, J.; Fisk, Z. Far-infrared investigations of η-Mo4O11: using a magnetic field to open the gap Ferroelectrics 2001 249, 51.
  27. Jones, B.; Olejniczak, I.; Dong, J.; Pigos, J.; Zhu, Z.-T.; Garlach, A.; Musfeldt, J.;* Koo, H.-J.; Whangbo, M.-H.; Schlueter, J.; Ward, B.; Morales, E.; Kini, A.; Winter, R.; Mohtasham, J.; Gard, G. Optical spectra and electronic band structure calculations of β-(ET)2SF5RSO3 (R = CH2CF2, CHFCF2, and CHF): Changing electronic properties by chemical tuning of the counterion Chem Mater 2000 12, 2490.
  28. Zhu, Z.-T.; Chowdhary, S.; Long, V.; Musfeldt, J.;* Koo, H.-J.; Whangbo, M.-H.; Wei, X.; Negishi, H.; Inoue, M.; Sarrao, J.; Fisk, Z. Polarized optical reflectance and electronic structure of the charge-density-wave materials β- and γ-Mo4O11 Phys Rev B 2000 61, 10057.
  29. Baker, S.; Dong, J.; Li, G.; Zhu, Z.-T.; Musfeldt, J.;* Schlueter, J.; Kelly, M.; Daugherty, R.; Williams, J. Infrared studies of low-temperature symmetry breaking in the perrhenate family of ET-based organic molecular conductors Phys Rev B 1999 60, 931.
  30. Long, V.; Zhu, Z.-T.; Musfeldt, J.;* Wei, X.; Koo, H.-J.; Whangbo, M.-H.; Jegoudez, J.; Revcolevschi, A. Polarized optical reflectance and electronic band structure of α-NaV2O5 Phys Rev B 1999 60, 15721.
  31. Olejniczak, I.; Jones, B.; Zhu, Z.-T.; Dong, J.; Musfeldt, J.;* Schlueter, J.; Morales, E.; Geiser, U.; Nixon, P.; Winter, R.; Gard, G. Optical properties of β′′-(ET)2SF5RSO3 (R=CH2CF2, CHFCF2): Changing physical properties by chemical tuning of the counterion Chem Mater 1999 11, 3160.
  32. Pigos, J.; Zhu, Z.; Musfeldt, J.* Optical properties of a supramolecular assembly containing polydiacetylene Chem Mater 1999 11, 3275.
  33. Zhu, Z.; Musfeldt, J.;* Wang, Y.; Sarrao, J.; Fisk, Z.; Negishi, H.; Inoue, M. Infrared study of the broken symmetry ground states in β-Mo4O11 Synth Met 1999 103, 2238.
  34. Zhu, Z.; Long, V.; Musfeldt, J.;* Wei, X.; Sarrao, J.; Fisk, Z.; Negishi, H.; Inoue, M.; Koo, H.; Whangbo, M. High field optical response of η-Mo4O11 J Phys IV 1999 9, 251.

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Facilities

  • Glovebox system equipped with thermal evaporator and spincoator.

glovebox

  • Sample cleaning setup (oxygen plasma, Laminar-flow hood, 18M  DI water system)
  • Chemical synthesis setup for air-sensitive reactions (Schlenk lines).
  • Home-built photovoltage and photocurrent transient setup for photovoltaic cells.
  • Keithley 2612 dual channel source meter for electric characterization.
  • UV lamp system and yellow-light lab for photo lithography and patterning.
  • Probe station for probing the electronic devices.
  • Home-made gas sensing setup and two mass flow controllers.
  • Perkin-Elmer Lambda-650 UV/Vis spectrometer.
  • KLA-Tencor D100 profilometer.
  • Nanoimprint Technology CNI nanoimprint tool.

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Openings

One research assistantship  is available starting in Fall 2014. The position is for a student who is interested in chemical and biological sensors based on organic semiconductors and/or conjugated polymers.  The student will enroll in the Biomedical Engineering Ph.D. Program (http://www.sdsmt.edu/BME/) at SDSMT, and will work on preparation and fabrication of conjugated polymer nanostructures, integration of conjugated polymer with biological species such as enzymes and DNAs in electrochemical transistor devices, and investigation of the potential chemical/biological sensing applications of these advanced materials and devices.  Student with a multidisciplinary background in chemistry, nanotechnology, or materials science is preferred.  If you are interested in the position, please send your cover letter and c.v to zhengtao.zhu@sdsmt.edu. 

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Sponsors

NASANSF     ACS
                        PRF                ResearchCorp

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Last updated: 1/8/2014





 
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