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Solar energy, as a clean, abundant and economical energy source, has huge potentials to replace fossil fuels in the generation of mass energy. Dye-sensitized-solar-cells (DSSCs) have emerged as one of the most promising technologies for solar energy conversion. In these systems, a thick nanoparticle film, which is usually constructed with metal oxide such as TiO2, provides a large surface area for the adsorption of light-harvesting dye molecules. In a typical operation of DSSC, dye molecules adsorbed on the semiconductor surface are promoted to their excited state by absorbing light. The excitons are thus created and split at the nanoparticle interface and the electrons are injected into the film. The charges migrate through the nanoparticle film and are collected at a transparent conducting electrode (electrons) and Pt electrode (holes).
In this project, we will design and synthesize new classes of porphyrin and Ru-polypyridyl-based supramolecules with the purpose to expand their applications as nanosized molecular devices for solar energy conversion and as components in photonic devices. Two of the major concerns in developing dye-sensitizer molecular systems are: broad spectral overlap with solar irradiation and efficient electron-transfer within the system. To achieve the first goal, molecules with expanded p-systems are desired; to achieve the latter is somewhat more complicated as many factors are involved, however, the regular arrangement of chromophores within one molecule is encouraged. Fine tuning the molecular system to obtain better understanding of structure-function relationship is still a hotly pursued topic.
We are closely collaborating with two other research groups (Dr. Zou and Dr. Kerr) at Miami University on DSSCs. We are currently investigating the inner cell kinetics and dye/ZnO interactions to gain further insight of ZnO-based DSSCs. We endeavor to develop and optimize DSSCs based on both TiO2 nanoparticles and ZnO vertical aligned nanowires to attain cell efficiencies higher than 12%. |
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Reference
- Robertson, N. Optimizing Dyes for Dye-Sensitized Solar Cells. Angew. Chem. Int. Ed. 45, 2338-2345 (2006).
- Lewis, N.S.; Nocera, D.G. Powering the Planet: Chemical Challenges in Solar Energy Utilization. PNAS 103, 15729-15735 (2006).
- Clifford, J. N.; Palomares, E.; Nazeeruddin, Md. K.; Thampi, R.; Gratzel, M.; Durrant, J. R. Multistep Electron Transfer Processes on Dye Co-sensitized NanocrystallineTiO2 Films. J. Am. Chem. Soc. 126, 5670-5671 (2004).
- Gratzel M. Photoelectrochemical Cells. Nature 414, 338-344 (2001).
- O'Regan, B.; Gratzel M. A Low-Cost, High-Efficiency Solar Cell Based on Dye-Sensitized Colloidal TiO2 Films. Nature 353, 737-740 (1991).
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