Pursuing Plant Power

Chemical engineers are looking to leaves as they try to make better, more efficient solar cells.

By Victoria Tang|Monday, May 09, 2011
A new flexible solar cell uses plant-based ingredients to gather energy.
Image Courtesy: Orlin Velev

In a quest to build a better solar cell, North Carolina State University chemical engineer Orlin Velev is borrowing from nature’s experts in collecting the sun’s energy: leaves. Starting with the natural pigments that help plants harvest solar rays, Velev and his team have crafted a flexible, nontoxic photovoltaic device that he hopes could eventually generate clean electricity far more cheaply than today’s silicon-based solar panels.

Velev’s one-square-inch proto­types consist of light-sensitive molecules—including the photosynthesis powerhouse chlorophyll—embedded in a water-based gel sandwiched between copper and plastic electrodes. Unlike traditional solar cells, many of which contain toxic elements such as cadmium, the biologically derived materials in Velev’s device can be safely released into the environment after use. The cell’s flexibility could make it an ideal choice for covering irregular surfaces; large pieces could even be rolled up or folded for easy transportation.

“This is a totally different way of thinking compared to a semiconductor cell, which is solid and expensive,” Velev says. In the next stage of development, he aims to boost the efficiency of the design, which is currently less than one percent of that achieved by top-performing silicon solar cells.

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