New solar energy materials
Silicon is the most developed solar energy material, but not the most favourable imaginable. For future photovoltaic applications much stronger light absorbing, and simultaneously environmentally friendly semiconductors are needed. I concentrated on semiconducting compounds, in which light is not breaking essential chemical bonds (as happens in silicon). Examples are molybdenum sulphide, MoS2, tungsten sulphide, WS2, and iron sulphide, FeS2, (e.g. ref. 23, 26, 54, 64, 74, 327). The proposed materials have demonstrated high quantum conversion efficiency, but for reasonable energy efficiency in technical devices their material technology still needs further development.
Figure: Pyrite, iron sulphide, is a fascinating potential solar energy material (above), and also serves as chemical energy for bacteria such as Leptospirillum ferrooxidans (below,a), which, when grown on pyrite, transforms it into nan-particles(b, c) before extracting its energy for carbon dioxide fixation. Pyrite may have served as material catalysing evolution of life.