71st SWRM/67th SERMACS

  Exploring All Directions

  Memphis, Tennessee

  November 4-7, 2015

“Doping Ge quantum dots for solar applications”

Brittany L. Oliva-Chatelain and Andrew R. Barron

Department of Chemistry
Rice University
6100 Main St. MS60
Houston, TX 77005

Several methods of doping germanium quantum dots were investigated for future use in solar cell applications. Doping the area surrounding the quantum dots in a silica matrix was not successful, and neither was modifying the outside layer of the quantum dot. Doping the quantum dot during synthesis was successful with phosphorus but was unsuccessful with boron or gallium. Further investigation indicates that the phosphorus is on the surface rather than inside the particle. Efficiency testing of these particles shows that the position of the dopant does not affect its ability to enhance the photoresponse of the quantum dots.

Activation of the molecular nanocluster FeMoC-EtOH in growth of carbon nanotubes
Gibran L. Esquenazi and Andrew R. Barron
Department of Chemistry
Rice University
6100 Main St. MS60
Houston, TX 77005

Chirality controlled growth of carbon nanotubes (CNTs) is of interest for numerous applications due to the superlative properties they exhibit as consequence of their chirality. A possible route for chiral specific growth is the use of uniform critically-sized catalysts under tightly controlled reaction conditions. Here we systematically investigate the hydrogen gas concentration and growth temperature influences on the “activation” of the molecular nanocluster catalyst FeMoC-EtOH [HxPMo12O40H4Mo72Fe30(O2CMe)15O254(H2O)98-x(EtOH)x] (where is x is calc. to be 30) in the growth of carbon nanotubes. The FeMoC-EtOH catalyst was demonstrated to be “activated” when the hydrogen gas concentration and growth temperature were sufficient enough to completely reduce the catalyst nanoparticles. The observations from prior work with FeMoC will be discussed with respect to these results in the aim of optimizing CNT growth.

Functionalization of Single Wall Carbon Nanotubes with Group 6 Metals

Kourtney Wright and Andrew R. Barron
Department of Chemistry
Rice University
6100 Main St. MS60
Houston, TX 77005

Single wall carbon nanotubes (SWNTs) have been shown to have high ampacity and long mean-free path lengths, making them attractive for electronic devices. Before nanotubes can be utilized in devices, multiple obstacles need to be overcome. As produced, SWNTs are a mixture of semiconducting and metallic types, which form Schottky barriers where the dissimilar tubes cross. This decreases the conductivity of SWNT fabrics and films. Attempts at separating SWNTs has proved to be challenging and results in contamination, damage, and low yields. This work is focused on functionalizing SWNTs with Cr0, Mo0, and W0 in order to bridge the resistive SWNT-SWNT and SWNT-contact junctions, thus, eliminating the need for SWNT separation. The effectiveness of this approach is tested by measuring the resistance of functionalized SWNT thin films on Si wafers using the four point probe method. These materials were characterized using infrared (IR) spectroscopy, X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), and energy dispersive X-ray spectroscopy (EDS).