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Individual protein complex generates electric current

Solar cell consisting of a single molecule

Graphical image of a photosystem I-complex which is lit by the tip of a optical near-field microscope
Photosystem-I (green) is optically excited by an electrode (on top). An electron then is transferred step by step in only 16 nanoseconds. Image: Christoph Hohmann (NIM)

Research news

Photosynthesis allows plants to convert light into chemical energy. Utilizing this process to produce electrical energy is a research goal worldwide. Now a team of scientists at the Technische Universität München and the Tel Aviv University has succeeded in directly deriving and measuring the photoelectric current generated by single molecules of the photosystem I.

As plant photosynthesis is the basis of life, re-engineering of this process for power generation is a big dream of researchers around the world. A team of scientists at the TU München, led by Joachim Reichert, John Barth (Cluster of Excellence Munich-Centre of Advanced Photonics) and Alexander Holleitner (Cluster of Excellence Nanosystems Initiative Munich) in cooperation with Itai Carmeli (Tel Aviv University), has now developed such a process in the nano-scale.

In a first step they fixed molecular complexes of the plant photosystem I on a gold surface. Then they coated an extremely fine glass tip, as it is used for near-field microscopy, with an ultrathin layer of gold. While the glass tip directs the light exactly to the protein to be examined, the gold layer forms the counter electrode. Thus the photosystem I protein complex acts as a highly efficient light-driven electron pump and could serve as a power generator in nano-electrical components.