Reviewed by Lexie CornerJul 23 2024
In a new study published in Nature Sustainability, researchers at the US Department of Energy’s (DOE) Argonne National Laboratory, along with collaborators at the University of Chicago, Purdue University, and Yale University, developed a method to design luminescent polymers with high light-emitting efficiencies from the start that are both recyclable and biodegradable.
New method allows design of light-emitting semiconductors that are both biodegradable and recyclable. Image Credit: Jie Xu and Yukun Wu.
Luminescent polymers, a family of flexible materials containing light-emitting molecules, are employed in various electronics, from your car's navigation display to the screen you are reading on. They are distinguished by their ability to produce light and fantastic flexibility and stretchability, demonstrating enormous potential in a wide range of applications.
However, after these devices have served their purpose, they are abandoned and end up in landfills or buried underground. Recycling electronic trash is complicated and requires costly and energy-inefficient procedures.
Although there is an economic motivation to recycle essential semiconducting materials—in this example, luminescent polymers—there has been no technique to accomplish this due to the difficulty of developing such materials at the molecular scale.
The motivation for the study was to overcome this difficulty.
The researchers added tert-butyl ester, a chemical that degrades in the presence of heat or mild acid, to the luminescent polymers.
Simply put, this chemical retains the material’s excellent light-emitting properties while allowing for recycling.
The scientists subsequently tested the material’s external quantum efficiency, a measure of light source performance. Its electroluminescence score was 15.1 %, ten times higher than the current degradable luminous polymers.
This novel polymer can break down at the end of its useful life in two ways: either in a mildly acidic environment (about the pH of stomach acid) or in a reasonably modest heat treatment (above 410 F). The resultant materials can be separated and reworked to create new materials for future use.
We were able to make this material biodegradable and recyclable without sacrificing the functionality. This work serves as an important benchmark in addressing the urgent need for sustainability in the design of future electronics.
Jie Xu, Project Lead and Scientist, Center for Nanoscale Materials, Argonne National Laboratory
The team’s goal is to make future electronics more sustainable (that is, easier to break down or recycle) rather than simply designing for present functionality. They also intend to broaden the use of these products to other sectors.
Design is still compatible with processibility, and in the end, you have to use this in real applications.
Yuepeng Zhang, Study Co-Author and Materials Scientist, Argonne National Laboratory
The researchers believe that this new polymer will be applicable to existing technologies, such as displays and medical imaging, enabling new applications.
The next stage in expanding the technology is to move it from the lab to devices like mobile phones and computer screens, where it will be tested continuously.
The team stated that this is merely the first stage in the process, but with electronic trash, every step matters. Xu expects that greater attention will be devoted to designing electronics with recyclability in mind, especially given the success of the depolymerization proof of concept.
Xu added, “This is a $46 billion-a-year industry, and it is only growing. By 2032, the industry is estimated to grow to $260 billion. With this method, we can eliminate this type of electronic waste that would otherwise be piling up in landfills.”
Additional Argonne authors include Wei Liu, Aikaterini Vriza, Hyocheol Jung, Shiyu Hu, Benjamin T. Diroll, Richard D. Schaller, and Henry Chan. Other authors include Yukun Wu and Sihong Wang (Argonne, Purdue University), Cheng Zhang, Glingna Wang (University of Chicago), Du Chen, Peijun Guo (Yale University) and Jianguo Mei (Purdue University).
The study was funded by the Argonne Laboratory Directed Research and Development award, the National Science Foundation, and the US Air Force Office of Scientific Research.
Journal Reference:
Liu, W., et. al. (2024) Depolymerizable and recyclable luminescent polymers with high light-emitting efficiencies. Nature Sustainability. doi:10.1038/s41893-024-01373-z