Plasmon-enhanced solar Photoconversion devices

• Applicant: Dr. Isabell Thomann
• Subject Area: Physical Chemistry of Solids and Surfaces, Material Characterisation
• Term: from 2009 to 2012
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 132586780

The proposed project aims to dramatically improve the efficiency (> 15%) of direct solar-hydrogen production devices based on the well-established photocatalyst TiO2. To this end, we seek to circumvent the key drawback of TiO2: a 3 eV wide bandgap that only allows a small fraction (< 4%) of the solar spectrum to be utilized. The central idea is to employ the unique optical properties of metal nanostructures (i.e. light-induced plasmon excitations) to efficiently concentrate sunlight near the surface of a TiO2 film. In this way, optical absorption close to the TiO2 surface is enhanced, precisely where the photo-generated electron-hole pairs are split and the relevant reactions are taking place. In a first stage, engineered metal nanostructures will be introduced onto active TiO2 films by thin film deposition / lithography techniques, with the goal to optimize the photo conversion efficiency of thin (< 100 nm) TiO2 films in the ultraviolet region. The second stage is aimed to extend catalytic activity into the visible range using dopants in TiO2, in combination with optimized metallic light concentration structures. While dopants typically reduce the electrical properties of TiO2, light concentration enables much thinner cell structures, circumventing the typical trade-off between electrical and optical performance. In the final stage, we will demonstrate the scalability of our techniques using self-assembled metal nanostructures. If successful, this work will enable a new path towards massive production of clean solar fuel.

• DFG Programme: Research Fellowships
• International Connection: USA
• Host: Professor Mark L. Brongersma, Ph.D.