Wednesday, June 30, 2004

Move over, Popeye

Scientists at the Massachusetts Institute of Technology have created a solar cell that uses photosynthetic proteins from spinach to convert light into energy. A team of biologists and engineers led by Marc Baldo of MIT extracted proteins from the chloroplasts of spinach leaves and the bacterium Rhodobacter sphaeroides. Molecular biologist Shuguang Zhang developed a new material consisting of synthetic peptides that self-assemble into a cell membrane-like structure. The synthetic membrane stabilises the extracted proteins and allows them to retain their function. The solar cell also contains an organic semiconductor and two electrodes, one of silver and and the other of Indium Tin Oxide (IN2O3:SnO2). The photosynthetic proteins absorb photons of certain frequencies and send excited electrons through the semiconductor to the silver electrode, creating the current that powers the device.

What's so great about this invention? The efficiency is far lower than that of currently available solar cells, though the inventors are working on improving that. Professor Baldo believes that the cell can be made cheap and easy to manufacture, and eventually power laptops and similar electronic devices. Unlike conventional solar cells which degrade over time, the protein-based cell could be self-repairing. Also, research along these lines is expected to provide scientists with a greater understanding of the mechanisms of natural photosynthesis.

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