Date of Graduation

Summer 2011

Degree

Master of Science in Materials Science

Department

Physics, Astronomy and Materials Science

Committee Chair

Lifeng Dong

Keywords

photo-electrochemical cells, photovoltaic cells, dielectrophoresis, carbon nanotubes, photoactive materials

Subject Categories

Materials Science and Engineering

Abstract

In this work I set out to investigate the electrical properties and photocurrent generating capabilities of carbon nanotubes and photoactive materials for use in photovoltaic cells and photo-electrochemical cells. Three different methods of fabrication were employed: dielectrophoresis, vacuum filtration, and the doctor blade technique. These materials' properties were evaluated in both solid state devices and in solution (photo-electrochemical cells). For my experiments, it was determined that carbon nanotube/oxide nanoparticles were not viable in solid state devices because the samples demonstrated no obvious positive photo-response and the conductivity of the materials typically decreased under illumination. In addition, the morphologies of the deposits made by dielectrophoresis were neither predictable nor repeatable. However, my experiments demonstrated that for photo-electrochemical cells, the films for working electrodes made via vacuum filtration exhibit good adhesion to the conducting glass substrates and resist peeling. Carbon nanotubes enhance the photo-response of the materials used, with multi-walled carbon nanotubes typically performing better than single-walled nanotubes. It was concluded that cadmium sulfide provides high photocurrent generation capabilities due to its relatively narrow band gap. It was also determined that for working electrodes in photo-electrochemical cells, multilayered films demonstrate improved photoconversion due to the band gap alignment between zinc oxide and cadmium sulfide.

Copyright

© Johnanthan Scott Malone

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