A Flexible Solar Panel for Clothes

April 5 -- Forget about old concepts of a "power tie" or a "power suit." One day, clothing could provide electrical juice to energize a portable phone, hand-held computer, or portable music player.

Scientists at the University of California at Berkeley say their latest research work in producing cheap, plastic solar cells may lead to such stunning possibilities.

According to A. Paul Alivisatos, a chemistry professor and lead researcher on the project, the experimental solar cells use tiny rods of cadmium selenide, a material similar to those used in computer chips.

The rods measure just 7 nanometers — 7 billionths of a meter — wide and 60 nanometers long and are suspended in an organic polymer, or plastic. The mixture is then sandwiched between two electrodes, one of transparent plastic and the other of flexible aluminum.

The experimental cell works just like other commercially-available photovoltaic cell. When exposed to sunlight, the "nanorods" of cadmium selenide material yields an electron and a related "hole" or vacancy. The electrons move through the rod to the aluminum electrode while the hole moves toward the other electrode, creating "positive" and "negative" terminals, just like a battery.

And in lab tests, a prototype solar cell about 200 nanometers thick — one-thousandth the thickness of a human hair — can produce just over half the voltage of a common flashlight battery.

Cooler Production for Newer Applications

But where Berkeley's cells really differ from others is the way in which they are created.

"Today's high-efficiency solar cells require very sophisticated processing inside a clean room and complex engineering to make the semiconductor sandwiches," Alivisatos says. "And because they are baked inside a vacuum chamber, they have to be made relatively small."

But Alivisatos says the nanorods of the tiny solar cells are created in a simple laboratory flask at room temperatures. That not only cuts out the need — and cost — for complex ovens and manufacturing procedures, but could allow for unique uses.