Chemistry Based Next Generation Solar Cells
Yasuhiro Tachibana, Osaka University
Photovoltaics have been recognized as an alternative or ultimate energy source to fulfill our increasing energy demand. Although now commercially available, in order to replace fossil energy, there still remains great improvement with their efficiency and cost. An approach is (i) to introduce economically viable materials and fabrication methods, or (ii) to design the cell structure on nanometer scales.
Our current research focuses on developing a novel solar cell structure by combining nanostructural metal oxides (titanium dioxide, etc.) and photoactive semiconductor nanomaterials (semiconductor quantum dots, conducting polymer, etc.), whilst controlling electron transfer rates at the hetero-junction interfaces.
2. Structural and Thermodynamic design
The structural design is based on sensitization of a wide band gap metal oxide by photoactive materials. If the nanostructured film consists of the metal oxide nanoparticles, an effective surface area is significantly enhanced, thereby achieving large absorbance of the sensitized film. The potential energy level of each component must be arranged thermodynamically to extract electrons efficiently from the nanostructured electrode. The efficiency improvement is dependent on the balance between the fast forward and the slow electron transfer reactions.