Photoelectrochemical cells convert sunlight into electricity, but their light-absorbing dyes, called chromophores, eventually degrade because of sunlight exposure. For plant cells, the degradation of chromophores isn’t a big deal – they simply self-regenerate.

Now, Purdue researchers are in the early stages of creating a solar cell that self-repairs in a way that is similar to a plant’s natural photosynthetic systems. Single-wall carbon nanotubes, anchored to strands of DNA, act as the “molecular wires” in the light harvesting cells. The DNA is engineered to have specific nucleotides that recognize chromophores and attach to them. Photo-damaged chromophores then may be removed by using chemical processes or by adding new DNA strands with different nucleotide sequences.

The work looks very interesting and could ultimately lead to a photoelectrochemical cell that operates at full capacity indefinitely.

Scientists at the University of New South Wales (UNSW, Sydney, Australia) developed a process to boost the efficiency of solar cell technology that also lowers the total cost. The UNSW researchers deposited a thin film of silver onto a solar cellÂ’s surface and then
heated it to 200 degrees Celsius. This broke the film into tiny “islands” of silver that boosted the cell’s light-trapping ability. The advance could see the price of an installed solar system for an average house fall from around $20,000 to $15,000 (Australian).

“Most thin-film solar cells are between eight and 10% efficient,” said Dr. Kylie Catchpole, a co-author of the study, “but the new technique could increase efficiency to between 13 and 15%.”

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A self-biased solar cell is available that provides improved conversion efficiency. Loss of carriers at the back surface of the battery is decreased, and open circuit voltage and quantum efficiency near a long wavelength are increased.
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An available technology introduces an electron-blocking layer between the two electrodes of a photoactive electronic device such as a solar cell. The electron-blocking layer prevents the recombination of electrons and holes.
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Georgia Tech researchers have developed a new protoype engine that uses up to 40% less fuel by running on solar power while in space and by fine-tuning exhaust velocity.

The key to the engine improvements is the ability to optimize the use of available power. A traditional chemical rocket engine (attached to a satellite ready for launch) runs at maximum exhaust velocity until it reaches orbit, i.e., first gear.

The new engine allows ground-control units to adjust the engine’s operating gear based on the immediate propulsive need of the satellite. The engine operates in first gear to maximize acceleration during orbit transfers and then shifts to fifth gear once in the desired orbit. This allows the engine to burn at full capacity only during key moments and conserve fuel.

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