Faculty Profile

Faculty Profile of Neal Armstrong

Neal Armstrong

Professor

Email: nra@email.arizona.edu
Building: CSB 218
Phone: 520-621-8242

Honors


  • Leading Edge Researcher, University of Arizona, 2011
  • Galileo Circle Fellow - College of Science, University of Arizona, 2011
  • Alexander von Humboldt Senior Research Prize - T.U. Dresden & MPIP-Mainz, 2002
  • NSF-Chemistry Special Award for Creativity, 2000
  • Career Teaching Award, College of Science, University of Arizona, 1996

Education and Appointments


  • B.S. 1970, Chemistry, University of New Mexico
  • Ph.D. 1974, Analytical Chemistry, University of New Mexico

Research Interests


  • Analytical
  • Energy Science
  • Materials and Polymer Chemistry
  • Surfaces and Solid State

Research Summary

Molecular Assemblies/Organic Electroluminescent and Photovoltaic Materials/Interfacial Science/Electrochemistry


For More Information please visit the CIS:SEM website




RECENT RESEARCH HIGHLIGHTS:

Recent studies of organic solar cells have focused on heterojunctions based on near-IR absorbing phthalocyanines (Pc) and C60, and the impact of phase changes of the Pc on photovoltaic performance. Increases in short-circuit photocurrent (J SC) are accompanied by changes in open-circuit photopotential (V OC), which correlated with changes in frontier orbital energy offsets, determined by UV-photoelectron spectroscopy (UPS).
Surface/interface characterization techniques, such as UPS/XPS and conducting tip AFM (C-AFM) are essential components of our research studies of organic/organic’ heterojunctions, and the heterojunctions between transparent conducting oxides (TCO) and organic films.
We have recently demonstrated the formation of highly ordered phthalocyanine thin films, using solution deposition of Pcs with H-bonding side chains. C-AFM studies have allowed the elucidation of the conductivity per Pc layer – leading to formation of new PV devices based on these ordered materials.
We have recently shown that new photovoltaic poly(thiophene) materials can be grown, and nano-textured, via electrodeposition. Device performance is directly correlated with the degree of electrochemical doping of the polymer film.
Semiconductor nanoparticles (e.g. CdSe) can be ligand-capped with electroactive functional groups, allowing for their electrochemical incorporation into polymer hosts. The resultant thin film materials can be used as photoelectrochemical catalysts for H 2-production, or as sensitizers in new hybrid material solar cells.
Organic light emitting diodes can be combined with organic photovoltaic detectors to create new chemical sensor platforms, emphasizing the convenience and simplicity of an all on-chip platform, where light source and detector are combined to do ATR spectrometry, refractometry and spectroscopy.


Selected Publications

  • "Selective Interlayers and Contacts in Organic Photovoltaic Cells," Erin L. Ratcliff, Brian Zacher, and Neal R. Armstrong, J. Phys. Chem. Letters - Perspective - Invited, in press. 2011

  • "Planar and Textured Heterojunction Organic Photovoltaics Based On Chloroindium Phthalocyanine (ClInPc) Versus Titanyl Phthalocyanine (TiOPc) Donor Layers," Weining Wang, Diogenes Placencia, Neal R. Armstrong, Organic Electronics, 12, 383-393, (2011).

  • "Potential-modulated attenuated total reflectance (PMATR) characterization of charge injection processes in monolayer-tethered CdSe nanocrystals," Zeynep Ozkan Araci, Clayton R. Shallcross, Neal R. Armstrong and S. Scott Saavedra, JPC Letters, 1, 1900-1905, (2010).

  • "Photoemission spectroscopy of tethered CdSe nanocrystals: Shifts in ionization potential and local vacuum level as a function of nanocrystal capping ligand," Andrea Munro, Brian Zacher, Amy Graham, Neal R. Armstrong, ACS Applied Materials and Interfaces, 2, 863-869, (2010).

  • "A Planar, Chip-Based, Dual-Beam Refractometer Using an Integrated Organic Light Emitting Diode (OLED) Light Source and Organic Photovoltaic (OPV) Detectors," Erin L. Ratcliff, P. Alex Veneman, Adam Simmonds, Brian Zacher, Daniel Huebner, S. Scott Saavedra, Neal R. Armstrong, Analytical Chemistry, 82, 2734-2742, (2010).

  • "Work function control of hole-selective polymer/ITO anode contacts: an electrochemical doping study," Erin L. Ratcliff, Paul A. Lee, and Neal R. Armstrong, (invited for themed issue on Interface Engineering of Organic and Molecular Electronics, 20, 2672-2679 (2010).

  • "Photoelectrochemical Processes in Polymer-Tethered CdSe Nanocrystals," R. Clayton Shallcross, Gemma D. D'Ambruoso, Jeffrey Pyun, Neal R. Armstrong, J. Amer. Chem. Soc., 132, 2622-2632 (2010).

  • "Tuning the Effective Work Function of Gold and Silver Using ω-Functionalized Alkanethiols: Varying Surface Composition Through Dilution and Choice of Terminal Groups," Dana M. Alloway, Amy L. Graham, Xi Yang, Anoma Mudalige, Ramon Colorado, Jr., Vicki H. Wysocki, Jeanne E. Pemberton, T. Randall Lee, Ronald J. Wysocki, Neal R. Armstrong, Journal of Physical Chemistry C, 113, 20328-20334 (2009).

  • "Evaluation of Transparent Carbon Nanotube Networks of Homogeneous Electronic Type," Roderick K. Jackson, Andrea Munro, Kenneth Nebesny, Neal R. Armstrong, Samuel Graham, Nano Letters, 4, 1377-1384 (2010).

  • "Oxide contacts in Organic Photovoltaics: Characterization and Control of Near-Sruface Composition in Indium-Tin Oxide (ITO) Electrodes," Neal R. Armstrong, P. Alex Veneman, Diogenes Placencia, Erin Ratcliff, Michael Brumbach, Accounts Chemical Research(Invited), 42, 1748-1757 (2009).

  • "Organic/Organic' Heterojunctions: Organic Light Emitting Diodes and Organic Photovoltaic Devices," Neal R. Armstrong, Weining Wang, Dana M. Alloway, Diogenes Placencia, Erin Ratcliff, Michael Brumbach, Invited Review, Marcromol. Rapid Commun., 30, 717-731 (2009).

  • "Organic Photovoltaic Cells Based On Solvent-Annealed, Textured Titanyl Phthalocyanine/C60 Heterojunctions," Diogenes Placencia, Weining Wang, R. Clayton Shallcross, Kenneth W. Nebesny, Michael Brumbach, Neal R. Armstrong, Advanced functional Materials, 19, 1913-1921 (2009).

  • "An Electroactive Fiber Optic Chip for Spectroelectrochemical Characterization of Ultra-Thin Redox Active Films," Brook M. Beam, Neal R. Armstrong, Sergio B. Mendes, Analyst, 134, 454-459 (2009).

  • "Organic Heterojunctions of Layered Perylene and Phthalocyanine Dyes: Characterization with UV Photoelectron Spectroscopy and Luminescence Quenching," Dana Alloway, Neal R. Armstrong, Appl. Phys. A., 95, 209-218 (2009).

  • "Electrodeposited, "Textured" poly(3-hexyl-thiophene)(eP3HT) Films for Photovoltaic Applications," Erin L. Ratcliff, Judith L. Jenkins, Ken Nebesney and Neal R. Armstrong, Chemistry of Materials, 20, 5796-5806 (2008).

  • "Hydrogen Bonded Phthalocyanine Aggregates," Niranjani Kumaran, Britt A. Minch, Neil Jacobsen, David F. O'Brien, Neal R. Armstrong, Chemistry of Materials, 22, 2491-2501 (2010).

  • "Phosphonic Acid Modification of Indium-Tin Oxide Electrodes: Combined XPS/UPS/Contact Angle Studies," Sergio A. Paniagua, Peter J. Hotchkiss, Simon C. Jones, Seth R. Marder, Anoma Mudalige, F. Fathima Saneeha Marrikar, Jeanne E. Pemberton, Neal R. Armstrong, J. Phys. Chem. C.(invited paper, Larry Dalton Festschrift) J. Phys. Chem C, 112, 7809-7817, (2008).

  • "Surface Composition, Electrical and Electrochemical Properties of Freshly Deposited and Acid-Etched Indium-Tin Oxide Electrodes," Michael Brumbach, P. Alex Veneman, F. Saneeha Marrikar, Thomas Schulmeyer, Adam Simmonds, Wei Xia, Paul Lee, Neal R. Armstrong, Langmuir, 23, 11089-11099 (2007).

  • "Modification of Indium-Tin Oxide Electrodes with Thiophene Copolymer Thin Films: Optimizing Electron Transfer to Solution Probe Molecules," F. Saneeha Marrikar, Michael Brumbach, Dennis H. Evans, Ariel Lebrón-Paler, Jeanne E. Pemberton, Ronald J. Wysocki, Neal R. Armstrong, Langmuir, 23, 1530-1542 (2007).

  • "Electrochemically Tunable Surface-Plasmon-Enhanced Diffraction Gratings and Their (Bio-)sensing Applications," Shengjun Tian, Neal R. Armstrong, and Wolfgang Knoll, Langmuir, 21, 4656-4660 (2005).


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