Western Michigan University1, Mechanical and Aeronautical Engineering Department, Kalamazoo, MI 49008 Wayne State University2, Department of Physics and Astronomy, Detroit, MI 48201
The objective of this project is to compare the efficiency of TiO2 based dye sensitized solar cells (DSSC) fabricated using TiO2 nanotubes that offer a large internal surface area, TiO2 thin films prepared by a simple spin-coating technique and TiO2 nano-particle thick film. TiO2 nanotubes were prepared by potentiostatic anodization of Ti metal foil in an electrolyte comprised of water, NH4F, and ethylene glycol using platinum as a counter electrode. TiO2 thin films were prepared by metalorganic decomposition technique using Ti-ethyl hexanoate as the precursor on FTO coated substrates. Nanoparticle thick films were grown on FTO coated glass substrate by doctor blade method using Degussa-25 TiO2 nanoparticles. Nanotubes and nanoparticular thin films were comprised of crystalline anatase TiO2 as evidenced by microRaman and XRD. A monolayer of high pure TiO2 nanoparticle was grown on all the samples using 0.2M TiOCl2 solution. A thin layer of ethanolic solution of ruthenium based dye (N-719) was coated over the TiO2 nanostructure. The dye molecules in this sensitized nanocrystalline assembly collect light of visible wavelengths and subsequently inject photoexcited electrons into the conduction band of the TiO2 semiconductor in a solar cell. DSSC works from the mechanism of a regenerative photoelectrochemical process. Solar cell was fabricated using dye sensitized TiO2 working electrode and Pt coated on ITO coated glass substrate as counter electrode. A liquid Iodide/Iodine based electrolyte is used to transfer electron from the counter electrode to dye by reducing the oxidized dye to its original state. After the devices are made, the dark current and the current in the presence of the light in the wave length region from 400 to 2000nm from a Quartz Tungsten Halogen lamp of 1 W at voltages ranging from -1 to 1 V are recorded. Also the power efficiency of the cell is evaluated from the I-V characteristics. The solar cell characteristics of these films are evaluated and will be discussed in this work.
Work supported by NSF-REU grant EEC-0552772
[Abstract (DOC)]