Blades of Grass Inspire Advance in Organic Solar Cells

Vertical nanopillars are ideal geometries for getting around the challenges of producing polymer architecture to boost power-conversion efficiency of light to electricity to power electronic devices.
Credit: UMass AMherst

UMass Amherst scientists use graphene in new energy conversion architecture

Using a bio-mimicking analog of one of nature’s most efficient light-harvesting structures, blades of grass, an international research team led by Alejandro Briseno of the University of Massachusetts Amherst has taken a major step in developing long-sought polymer architecture to boost power-conversion efficiency of light to electricity for use in electronic devices.

Briseno, with colleagues and graduate students at UMass Amherst and others at Stanford University and Dresden University of Technology, Germany, report in the current issue of Nano Letters that by using single-crystalline organic nanopillars, or “nanograss,” they found a way to get around dead ends, or discontinuous pathways, that pose a serious drawback when using blended systems known as bulk heterojunction  donor-acceptor, or positive-negative (p-n), junctions for harvesting energy in organic solar cells.

Briseno’s research group is one of very few in the world to design and grow organic single-crystal p-n junctions. He says, “This work is a major advancement in the field of organic solar cells because we have developed what the field considers the ‘Holy Grail’ of architecture for harvesting light and converting it to electricity.” The breakthrough in morphology control should have widespread use in solar cells, batteries and vertical transistors, he adds.

Briseno explains, “For decades scientists and engineers have placed great effort in trying to control the morphology of p-n junction interfaces in organic solar cells. We report here that we have at last developed the ideal architecture composed of organic single-crystal vertical nanopillars.” Nanopillars are nanoscale, engineered surfaces with billions of organic posts that resemble blades of grass, and like grass blades they are particularly effective at converting light to energy.

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