Date of Award
Doctor of Philosophy
Materials Science and Engineering
Organic solar cells (e.g., dye sensitized solar cells and organic-inorganic bulk heterojunction cells) are attracting considerable attention due to their low cost, easy processibility, and large scale fabrication capability. However, the solar energy conversion efficiency of these cells is low due to significant charge recombination and inefficient charge separation at the organic/inorganic interface. Thus, further improvement on the efficiency is necessary for the creation of low-cost devices.
In this context, we focus on the synthesis of highly ordered TiO2 nanotube arrays, which was subsequently utilized as photoanode in dye sensitized solar cells and quantum dot solar cells. The highly ordered TiO2 nanotube arrays not only provide a large interface area where excitons, the bound electron-hole pairs, may effectively dissociate, but also have two separate channels for efficient electron and hole transport. Surface engineering, i.e., TiCl4 treatment and oxygen plasma exposure, was combined in the first time to improve the solar energy conversion efficiency of dye sensitized TiO2 nanotube solar cells. With a nanotube film thickness of 14 ym and optimized surface treatment, an overall power conversion efficiency of 7.37 % were obtained when a ruthenium dye N-719 was used as photosensitizer; this performance is among the best for TiO2 nanotube based solar cells. In addition, a number of functional nanocrystals, including semiconducting CdSe quantum dots, ferroelectric BaTiO3 and PbTiO3 nanocrystals, multiferroic BiFeO3 nanocrystals were synthesized and characterized, which possess potential applications in solar cells, light emitting diodes, biosensors, thin-film capacitors, pyroelectric detectors, electrooptic modulators, transducers, actuators, and magnetically recorded ferroelectric memory.
Wang, Jun, "Nanostructured semiconducting, ferroelectric, and multiferroic crystals: synthesis, characterization and energy application" (2009). Graduate Theses and Dissertations. 10973.