Nanowires used for low-cost, efficient solar cells

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Tuesday, September 6th, 2011

Researchers from the Lawrence Berkeley National Laboratory of United States Department of Energy developed new low-cost yet efficient solar cells made of nanowires.

Lead researcher Peidong Yang developed a solution-based technique for production of core and shell nanowire solar cells using the semiconductors cadmium sulfide for the core and copper sulfide for the shell.

These cheap and easy to make nanowire cells have open-circuit voltage and fill factor values that are greater than conventional solar panels.

The open-circuit voltage and fill factor values determine that maximum energy that a solar cell can produce.

Moreover, the new nanowire solar cells have an energy conversion efficiency of 5.4 percent, which is similar to solar panels.

"This is the first time a solution based cation-exchange chemistry technique has been used for the production of high quality single-crystalline cadmium sulfide/copper sulfide core/shell nanowires," Mr. Yang said.

"Our achievement, together with the increased light absorption we have previously demonstrated in nanowire arrays through light trapping, indicates that core/shell nanowires are truly promising for future solar cell technology," he added.

Conventional solar cells are made from expensive crystal silicon wafers. Moreover, the production of solar cell is an energy intensive and costly process.

One of the alternatives to silicon wafers is the use of semiconductor nanowires. The technology renders a wide array of benefits such as better charge separation and collection ability. The nanowires can also be made from abundant materials available in the environment.

However, its low efficiency overshadows its benefits.

The researchers are now working to make the new technology commercially viable, the nanowire solar cells must reach an energy efficiency of at least 10 percent. The researchers believed that they can improve the energy efficiency of the solar cell nanowires by adding more copper sulphide shell material. If plausible, the technology could indeed lower the overall cost of the solar energy production.

The research was funded by D.O.E.s Office of Science. The research findings are published in the journal Nature Nanotechnology.

source: APEC-VC Korea