Stretchable Solar Cells Get a Boost from Common Rubber

New Material Promises Durable, Flexible Power for Wearable Tech

A common material found in wetsuits and hardware stores is dramatically improving the durability and flexibility of organic solar cells, potentially paving the way for widespread use in wearable electronics and beyond. Researchers have found a way to maintain efficiency even when the cells are repeatedly stretched.

A New Approach to Organic Solar Cell Design

Organic solar cells, known for being thin, lightweight, and printable, have long struggled with maintaining performance when bent or stretched. A team led by Tobin J. Marks at Northwestern University and Antonio Facchetti at the Georgia Institute of Technology has addressed this challenge by incorporating chloroprene rubber into the cell’s structure.

The key to improved performance lies in separating the molecules that absorb light and those that collect electrons. Traditionally, volatile chlorinated molecules were used for this purpose, but they tended to dissipate during manufacturing. The team’s innovation replaces these with non-volatile chloroprene rubber, which serves a dual purpose: enhancing electron flow and providing stretchability.

Chloroprene: A Surprising Solution

Marks believes the simplicity of the solution is its strength. “I imagine people saying, ‘Gee, chloroprene rubber, I can buy that at a hardware store; let me put that in my solar cell.’” The readily available nature of the material could significantly lower production costs and accelerate adoption.

The global market for wearable technology was valued at $115.2 billion in 2023 and is projected to reach $398.7 billion by 2032, according to a report by Grand View Research (Grand View Research, 2024). More durable and flexible power sources are crucial to meeting the demands of this rapidly expanding sector.

Balancing Efficiency and Flexibility

While adding 20% chloroprene rubber by mass does result in a slight decrease in efficiency – down to 15.6% – the cells demonstrate remarkable stability. They retain nearly 90% of their initial efficiency even after being stretched to 50% of their original size for 5,000 cycles.

“This efficiency maintenance even at high chloroprene loading is impressive. An optimization of mechanical demands and power generation will need to be weighed [for applications].”

—Brendan O’Connor, North Carolina State University

Justin Hodgkiss of Victoria University of Wellington praised the work as elegant and effective. “These devices are right up there with the very best reported devices in terms of efficiency, flexibility, and stability, all at once,” he stated.

The researchers suggest that chloroprene rubber could be integrated into a wide range of organic photovoltaic materials, offering a versatile pathway to more robust and adaptable solar energy solutions. Further research will focus on optimizing the balance between efficiency and flexibility for specific applications.