credit: U.S. Air Force
Solar cells are typically built from silicone, as the material is the most efficient for converting light into electricity, with a typical efficiency benchmark of around 22 percent. Organic photovoltaic cells (OPV)—made from carbon-based alternatives—are far cheaper to produce and offer much more flexibility than silicone-based cells. They consist of a photosensitive material that can be turned into an “ink” and printed onto polymers using a conventional printer.
However, they have not seen mainstream adoption primarily because they are far less efficient than silicone-based cells—typically converting light to electricity at less than half the efficiency rate of silicone.
However, a new study released in April demonstrates that researchers have engineered new forms of OPVs that can convert at close to the rate of silicone solar cells, currently reaching a maximum efficiency of 15%; researchers claimed that up to 25% could be possible.
In contrast to previous OPV cells, the high-efficiency cells rely on a “tandem cell” structure, in which two devices are built together in a single structure.
"We have two layers of active materials, each layer can absorb different wavelengths of light,” one of the authors, Dr Yongsheng Chen, from Nankai University in Tianjin, China, told BBC News. “That means you can use sunlight in the wider wavelengths or more efficiently and this can generate more current."
Why is this so significant? Here are two reasons:
Lower cost electricity
These OPV cells have the potential to significantly lower the cost to produce electricity. BBC News claims that with a 15% efficiency rating and a 20-year lifetime, OPV cells can produce electricity for less than 7 cents per kilowatt-hour, compared to a current average cost of 10.5 cents per kilowatt-hour for all electricity sources.
More flexible applications
As opposed to rigid silicone cells, OPVs can be printed directly onto other materials, opening up a world of potential applications. For instance, they can be stitched directly into clothing to power connected devices. They can also be attached to lightweight roofing materials that would not be able to accommodate heavier silicone cells, facilitating the use of solar electricity in developing countries. Their small size and flexibility also means that they can be used to power small electronics directly, such as portable phone chargers and smartwatches.
While OPV cells aren’t likely to gain market share over silicone solar cells in the immediate future, they hold great potential for the future of the solar electricity industry. The carbon-based materials used in OPV are affordable and can be easily printed to produce cells, making the manufacturing process cheaper and easier than with silicone cells. That means developing regions will be able to tap into the power of solar electricity to increase crop production, improve access to healthcare technology, and foster economic development through manufacturing, among many other use cases.
High-efficiency OPV cells aren’t quite ready for mass production: The study’s researcher, Dr. Chen, estimates that they will be commercially available in five years or less. When that time comes, OPV cells may prove to revolutionize the solar industry by lowering costs and improving worldwide accessibility.