The unit set the record in the Research Area “Creative research for clean energy generation using solar energy” (Research Supervisor: Masafumi Yamaguchi, Principal Professor, Toyota Technological Institute Graduate School of Engineering) as part of the Core Research of Evolutional Science & Technology (CREST) program sponsored by the Japan Science and Technology Agency (JST).
The highest energy conversion efficiency in dye-sensitized solar cells had remained at 11.1% since 2006. However, in this research, the NIMS Photovoltaic Materials Unit succeeded in improving conversion efficiency to 11.4% by increasing both the cell short-circuit current density and open circuit voltage. This is the highest value was certified by the public test center (AIST, Japan).
This new world record for highest conversion efficiency in dye-sensitized solar cells was made possible by the development of a new additive material which is capable of fully demonstrating a dye-sensitizing effect. By applying this additive to dye-sensitized solar cells, it was possible to improve the external quantum efficiency of the cell in the visible light region by approximately 80% and obtain a large short-circuit current density. The open circuit voltage could also be improved simultaneously with this. The adoption of this additive, which is different from the conventional type, realized the new world record for conversion efficiency.
In the future, the Photovoltaic Materials Unit will investigate the effect of the additive on the state of dye adsorption on TiO2 and the mechanism of charge transfer in the cell in order to further improve the efficiency. The NIMS researchers are aiming at even higher conversion efficiency by developing a more effective materials based on this result.
This research achievement was announced at the 72nd Fall Meeting of the Japan Society of Applied Physics (JSAP) on August 29, 2011.