Houman Yaghoubi

Publications

• "Surface chemistry of atmospheric plasma modified polycarbonate substrates."

  H. Yaghoubi, N. Taghavinia

  Applied Surface Science. 01/2011; 257:9836-9839.

• Application of Wide Band Gap Semiconductors to Increase Photocurrent in a Protein Based Photovoltaic Device

  Arash Takshi1, Houman Yaghoubi1, John D. Madden2, J. Thomas Beatty3

  Mat. Res. Soc. Symp. 2011 Fall Meeting; 01/2011

• Free-floating Reaction Centers (RCs) versus Attached Monolayer of RCs in Bio-photovoltaic Devices

  Houman Yaghoubi 1, Arash Takshi 1, Daniel Jun 2, Rafael Saer 2, John D. Madden 3, J. Thomas Beatty 2

  Mat. Res. Soc. Symp. 2011 Fall Meeting; 01/2011

• Nanomechanical properties of TiO2 granular thin films.

  Houman Yaghoubi, Nima Taghavinia, Eskandar Keshavarz Alamdari, Alex A Volinsky

  ACS applied materials & interfaces. 09/2010; 2(9):2629-36.

  Post-deposition annealing effects on nanomechanical properties of granular TiO2 films on soda-lime glass substrates were studied. In particular, the effects of Na diffusion on the films' mechanical properties were examined. TiO2 photocatalyst films, 330 nm thick, were prepared by dip-coating usi... [more] Post-deposition annealing effects on nanomechanical properties of granular TiO2 films on soda-lime glass substrates were studied. In particular, the effects of Na diffusion on the films' mechanical properties were examined. TiO2 photocatalyst films, 330 nm thick, were prepared by dip-coating using a TiO2 sol, and were annealed between 100 °C and 500 °C. Film's morphology, physical and nanomechanical properties were characterized by atomic force microscopy, X-ray photoelectron spectroscopy, X-ray diffraction, differential thermo-gravimetric analysis, and nanoindentation. Contrary to expectations, the maximum film hardness was achieved for 300°C annealing, with a value of 0.69±0.05 GPa. Higher annealing temperatures resulted in inferior mechanical properties. No pile-up or sink-in effects were observed with minimal creep for the 300 °C annealed sample. Considerable decrease in the amount of chemisorbed water was found with increasing annealing temperature, causing gel films densification, explaining the increasing trend of hardness with annealing temperature between 100 °C and 300 °C. DTA/TGA results also confirmed the weight loss and the endothermic reaction due to desorption of chemisorbed water. Decrease in hardness above 300 °C annealing is attributed to thermal diffusion of Na ions from the glass substrate, confirmed by nanoindentation tests on TiO2 films deposited on fused quartz, which did not exhibit hardness decrease after 300 °C annealing.

• Self cleaning TiO2 coating on polycarbonate: Surface treatment, photocatalytic and nanomechanical properties

  Houman Yaghoubi, Nima Taghavinia, Eskandar Keshavarz Alamdari

  Surface & Coatings Technology. 01/2010; 204:1562-1568.