While we are used to seeing all kinds of incremental gains in solar cell production cost and efficiency, here’s one that incorporates chemical biomimicry, although we hope this does not result in overfishing. Researchers at Queen Mary University of London’s School of Engineering and Materials Science have successfully created electricity-generating solar cells with chemicals found in the shells of shrimp and other crustaceans.
The materials chitin and chitosan, found in the shells, are abundant and significantly cheaper to produce than the expensive metals such as ruthenium, which is similar to platinum, that are currently used in making nanostructured solar-cells. Ruthenium is found in nature, often with the other platinum group metals, but commercially requires extraction from pentlandite, a sulfide of iron and nickel, which contains only small quantities of ruthenium.
Professor Magdalena Titirici, Professor of Sustainable Materials Technology at QMUL, said that “New techniques mean that we can produce exciting new materials from organic by-products that are already easily available. Sustainable materials can be both high-tech and low-cost.”
At this time the efficiency of the solar cells created with these biomass-derived materials is low, but after expected improvement the team sees a variety of market applications for low-cost solar cells, including wearable chargers for tablets, phones and smartwatches, and semi-transparent films over window glass.
The research team used a process known as hydrothermal carbonization to create the carbon quantum dots (CQDs) from the widely and cheaply available chemicals found in crustacean shells. They then coat standard zinc oxide nanorods with the CQDs to make the solar cells.
Dr Joe Briscoe, one of the researchers on the project, said: “This could be a great new way to make these versatile, quick and easy to produce solar cells from readily available, sustainable materials. Once we’ve improved their efficiency they could be used anywhere that solar cells are used now, particularly to charge the kinds of devices people carry with them every day.”
He adds that the chitin and chitosan would be extracted from waste material produced by the food industry. The waste shells and other parts can be collected, washed and ground, and the chitin can be extracted from mixture. The purification of chitin has the potential to be a simpler process, and likely would use less harmful materials, than those used in mining purification. Professor Titirici is also investigating materials that can be produced directly from the ground waste material without the need for purification, which also contains materials such as calcium carbonate.