Abstract

We will present progress towards the use of plasmonic metal nanostructures to enhance the efficiency of solar fuel generation [1]. In the past, solar-to-fuel-efficiencies have been limited because of a large mismatch in the length scales for optical absorption and carrier extraction. Future generations of photoelectrodes must employ cheap, earth-abundant absorber materials in order to provide a large-scale source of clean energy. These materials will likely have relatively poor electrical properties, so progress must be made in optimizing their absorption properties [2, 3]. We chose iron oxide (α-Fe₂O₃; hematite) [4] as a prototype system that shares many features with other candidate materials for future large-scale solar fuel production, and therefore anticipate that the results obtained in this study will be applicable to other materials systems as well. Hematite has relatively weak absorption in the 500–600 nm range (0.1 – 1 μm absorption length), very long compared to its minority carrier diffusion length on the order of 2-4 nm [5] or 20 nm [6].

© 2011 IEEE