US researchers develop recyclable solar cells from trees

March 30, 2013 2:50pm


With leaves naturally capturing sunlight and converting it to energy, is it any wonder that trees can make the most efficient solar cells?

Researchers from the Georgia Institute of Technology and Purdue University have developed recyclable solar cells derived from trees and plants.

“The development and performance of organic substrates in solar technology continues to improve, providing engineers with a good indication of future applications,” said Georgia Tech College of Engineering Professor Bernard Kippelen, who led the study.

Kippelen, director of Georgia Tech’s Center for Organic Photonics and Electronics (COPE), said this can lead to a truly recyclable, sustainable and renewable solar cell technology.

"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 life-cycle,” he said.

A provisional patent on the technology has been filed with the US Patent Office.

Kippelen said their next stage is to improve the power conversion efficiency to over 10 percent –  "levels similar to solar cells fabricated on glass or petroleum-based substrates.”

Purdue School of Materials Engineering associate professor Jeffrey Youngblood collaborated with Kippelen on the research.

Easily recyclable


In their work published in the journal Scientific Reports, the researchers said their organic solar cells can be recycled in water at the end of their lifecycle.

More importantly, the team said the organic solar cells reach a power conversion efficiency of 2.7 percent.

The organic solar cell is derived from plants such as trees, with the researchers fabricating them on cellulose nano-crystal (CNC) substrates.

A news release from Georgia Tech said the CNC substrates are transparent, allowing light to pass through them before being absorbed by a very thin layer of an organic semiconductor.

The solar cells can also be recycled by immersing them in water at room temperature.

"Within only minutes, the CNC substrate dissolves and the solar cell can be separated easily into its major components," it said.

By comparison, present "organic" solar cells are usually fabricated on glass or plastic, and are not as easily recyclable as the newly developed one.

While cells with paper substrates are more environment-friendly, their performance is limited. — LBG, GMA News