Novel materials can reduce solar power costs

While solar electricity generation has skyrocketed in the past five years, it still accounts for less than one percent of overall power generation in the United States. Materials costs for solar technologies have gone down, but not yet enough to be fully competitive with other fuels.

Those costs could drop further and the flexibility of solar technologies could increase due to the work of Duke University researchers. A team led by Dr. Adrienne Stiff-Roberts is investigating ways to use organic materials for solar power through an advanced technique known as matrix-assisted pulsed laser evaporation, or MAPLE. The project is supported by Duke’s Energy Initiative, which has provided seed grants to encourage a variety of innovative research projects.

Organic materials for solar technologies are currently less efficient and less durable than existing technologies employing silicon or gallium-arsenide, two leading materials. Because organic materials cost less and are more abundant, the potential for solar power around the world can be substantially expanded if researchers can increase the efficiency and durability of these organic materials.

The MAPLE technology allows Stiff-Roberts (pictured left), an associate professor of electrical and computer engineering at Duke’s Pratt School of Engineering, and her colleagues to place multiple layers of organic materials on top of one another in a solar cell. These layers then generate electricity in similar ways to existing technologies. Because organic materials are often made up of soluble solutions that can intermingle, layering them on top of one another has been a challenge – one that the MAPLE technique is able to overcome.

"Organic materials have the potential to be deployed in very novel ways," Stiff-Roberts explained. "They are more flexible than existing solar materials, and could be integrated into materials like paint, clothing or windows."

The researchers are currently examining how dense arrangements of silver nanocubes can be integrated into the organic materials deposited by MAPLE in order to improve absorption across the solar radiation spectrum. Existing research conducted by team member Dr. Maiken Mikkelsen, assistant professor of electrical and computer engineering and physics, has only examined the performance of single silver nanocubes. Stiff-Roberts and her colleagues seek to understand how different arrangements of these materials might work together to generate power more efficiently.

Stiff-Roberts uses the MAPLE technique for work on a wide range of applications, including military and commercial purposes. She and her colleagues became interested in solar technology because "it’s one of the grand challenges," she explained. "Making solar energy more affordable is a big, important problem."