New and Efficient Photosensitizers for Nanocrystalline TiO2 Based Dye Sensitized Solar Cells
PI: Dr. Duraisamy Kumaresan
Co-PIs: Dr. Nikhil K. Kothurkar, Dr. Yamuna
Sponsors: DRDO, ER & IPR
Dept./Center: Solar Energy and Optoelectronics Laboratory
Start Date: July 2010
A dye-sensitized solar cell (DSSC) is a thin-film type, low-cost alternative to the existing silicon solar cells in commercial market. The state of the art DSSC is fabricated by combining a panchromatic ruthenium dye photosensitizer, an iodine electrolyte, and a thick mesoporous titania film between electrodes. This DSSC produces photocurrent from sunlight with up to 11 % efficiency. Further improvement in the efficiency of DSSCs is currently under intense investigations in several laboratories around the world to meet quick payback time. One of the crucial components in DSSCs, the photosensitizers shows promising routes to improve the efficiency further.
Photosensitizers must have the following features for improving the current generation solar cells:
- The absorption spectrum of the photosensitizer should cover the whole visible region and even part of the near- infrared (NIR).
- For dye regeneration, the oxidized state level of the photosensitizer must be more positive than the redox potential of electrolyte.
- The photosensitizer should be photostable, and electrochemical and thermal stability are also required.
Based on these requirements, many different photosensitizers including metal complexes, porphyrins, phthalocyanines, and metal-free organic dyes have been designed and applied to DSSCs in the past decade. In the past, the team has prepared many new ruthenium (II), Iron (II) polypyridyl complexes and organic dyes for photosensitization purposes.
In the current project, several new photosensitizers based on Ru(II), Fe(II) complexes and some organic dyes are being synthesized. The better-performing photosensitizers will be tested for further improvement in solar cell efficiencies, and their physicochemical properties will be studied for better understanding of the photophysics of DSSCs containing new sensitizers.