Alexandru R. Biris

SOCl2 enhanced photovoltaic conversion of single wall carbon nanotube/n-silicon heterojunctions

We report solar cells based on high-density p-n heterojunctions between single wall carbon nanotubes (SWCNTs) and a n-type silicon wafer. Chemical modification by thionyl chloride of the SWCNT coating films was found to significantly increase the conversion efficiency by more than 45% through adjusting the Fermi level and increasing the carrier concentration and mobility. Electron-hole pairs are optically excited in the numerous heterojunctions formed between SOCl2-treated SWCNTs thin coating and n-type silicon substrate, and then split and transported through SWCNTs (holes) and n-Si (electrons), respectively.

Electrical and thermal properties of carbon nanotube polymer composite films

The electrical and thermal properties of carbon nanotubes (CNT)-polymer nanocomposite materials have been studied. The carbon nanostructures were analyzed by several analytical techniques, including Electronic Microscopy, Raman Spectroscopy, and X-Ray Photoelectron Spectroscopy. Carbon nanotubes were grown by catalytic chemical vapor deposition on metal/metal oxide catalytic systems using acetylene or other hydrocarbons. Raman Spectroscopy was used to analyze the CNT and CNT-polymer nanocomposite materials. The thermal and electrical properties of these CNT-polymer nanocomposite materials depend on the amount of CNTs in the polymer and also on the uniformity of the CNTs dispersed in the polymer. A reduction in electrical resistivity was observed, as the nanotubes concentration in the polymeric films increased, while optical transparency remained 85 % or higher relative to acrylic films without nanotubes.

Carbon Nanotube Based Electrically Conductive and Optically Transparent Thin Films

Highly electrically conductive and optically transparent thin films were fabricated on conventional glass substrates using different purified carbon nanotubes, single-wall (SWNT), double-wall (DWNT), and multi-wall (MWNT) carbon nanotubes. The starting carbon nanotube materials were first made into homogenous solution with either sodium cholate or dimethylformamide. Two different fabrication approaches, airbrushing and membrane filtration methods, were used and compared. The chemical modification of thionyl chloride was employed to further improve the optical and electric performance of the SWNT films. Additionally, the temperature dependence of the resistance measured on carbon nanotube networks has been investigated.