Solar cells made from trees are easily recyclable

recyclable solar cell from trees© Canek Fuentes-Hernandez / Georgia Institute of Technology

Scientists at Georgia Institute of Technology have developed a solar cell that is partially made from trees and what's even more impressive is that the cell can easily be recycled at the end of its life by merely being submerged in room temperature water.

The breakthrough comes from the team that last year developed the first all-plastic solar cell, except this time they've figured out how to use trees, or any other plant for that matter, in a cellulose nanocrystal (CNC) substrate in a solar cell. Using organic matter in the substrate means that at the end of the cell's life, being dunked in warm water for a few minutes will cause it to dissolve, leaving all the other components to separate easily for recycling.

“The development and performance of organic substrates in solar technology continues to improve, providing engineers with a good indication of future applications,” said Engineering Professor Bernard Kippelen, who is also the director of Georgia Tech’s Center for Organic Photonics and Electronics (COPE). “But organic solar cells must be recyclable. Otherwise we are simply solving one problem, less dependence on fossil fuels, while creating another, a technology that produces energy from renewable sources but is not disposable at the end of its lifecycle.”

Although solar cells help us to produce cleaner energy, they themselves can become e-waste at the end of their lives if not disposed of properly, so developing technologies that are easy to recycle is crucial.

Right now the solar cell has a conversion efficiency of 2.7 percent, which seems terribly low compared to crystalline silicon solar cells that have efficiencies in the 15 - 20 percent range, but it's actually the highest seen for an organic solar cell using renewable materials.

The team plans to get the conversion efficiency to over 10 percent by optimizing the optical properties of the solar cell’s electrode, which would make it competitive with other solar technologies.

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