Nanostructured Materials for Organic Photovoltaic Devices

• Author / Creator

  van Dijken, Jaron G

• This thesis outlines several new approaches to fabricating improved organic solar cell (OSC) designs. Glancing angle deposition (GLAD) was used to grow thin films of metal phthalocyanine (MPc) materials with columnar morphologies suitable for use in OSCs. Advanced substrate motion techniques were used to constrain column broadening during growth, in order to approach diameters comparable to the short exciton diffusion lengths in these materials. Substrate patterning was used to predefine growth sites for these columnar films, and thereby regulate column spacing and improve film uniformity. Increased column densities and decreased column diameters were achieved as a result.
  Integration of columnar films into OSCs was challenged by the sensitivity of MPc materials to the solvents used to cast the adjacent layer. Significant recrystallization of the films occurred when directly contacted by these solvents. Varying degrees of material mixing between layers were observed as a result of the solvents when casting the adjacent layer. This result provides an alternative approach to building a mixed active layer structure, which has so far only been possible via codeposition of vapors or polymer blending. Material mixing was shown to improve device performance, which led to photoconversion efficiencies of up to 3.0% when used in combination with a GLAD-structured MPc layer. This result stands among the best results achieved in the literature for these devices. Optimized devices were enabled by a careful evaluation of the degradation behavior and thickness effects of the various device layers.
  Argon plasma etching was used to structure planar MPc films and commercial indium tin oxide (ITO). Nanopillar features emerged in both cases, which are very attractive from an OSC perspective. The surface composition of these films was altered by the etching process, resulting in damaged film properties. The damage to MPc films was irreversible, preventing their ideal morphologies from improving OSC performance. For ITO, however, optical and electrical properties were recovered using a two-stage annealing process, leaving the films fully functional for use in a variety of optoelectronic devices.

• Subjects / Keywords

  • Thin films
  • Glancing angle deposition
  • Organic solar cell

• Graduation date

  Fall 2012

• Type of Item

  Thesis

• Degree

  Doctor of Philosophy

• DOI

  https://doi.org/10.7939/R3R402

• License

  This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.