The development of solar power has provided mankind with a renewable and alternative energy source without producing carbon emissions. However, the lack of a cost-effective and extensive system for storing electricity significantly limits its ability to supply energy on a larger scale.
A single solar cell, for instance, can only store several microseconds' worth of electricity.
This is what inspired a team of scientists at the University of California, Los Angeles (UCLA) to create a new technology that would allow solar cells to store energy for longer periods of time.
The new solar cell features a design similar to how plants produce energy through the process of photosynthesis.
"Biology does a very good job of creating energy from sunlight," Sarah Tolbert, a professor of chemistry at UCLA and a senior author of the study, explained. "Plants do this through photosynthesis with extremely high efficiency."
"In photosynthesis, plants that are exposed to sunlight use carefully organized nanoscale structures within their cells to rapidly separate charges - pulling electrons away from the positively charged molecule that is left behind, and keeping positive and negative charges separated."
Tolbert said this separation is vital in making sure the entire process is conducted efficiently.
For conventional solar cells to collect enough power from sunlight, engineers have to add silicon to each rooftop cell, which makes the system expensive to maintain.
Other solar power developers tried to substitute plastic for silicon materials to make it more affordable, but modern-day plastic cells are not as efficient as silicon in capturing energy. This is mainly because the negative and positive electric charges are often recombined even before they are converted into electricity.
Tolbert said their new technology keeps the separated charges apart from each other longer than conventional plastic materials, for days and up to several weeks.
The key components of their solar power system are its nano-sized fullerene acceptor and polymer donor. Sunlight is absorbed through the polymer donor, which then passes the electrons to its fullerene acceptor to generate electrical energy.
Compared with the disorganized look of conventional plastic materials known as organic photovoltaics, the UCLA design features neatly arranged elements that help prevent the loss of electrons during the storage process.
Study co-author Benjamin Schwartz said their system performs better when the charges are prevented from coming back together. He added that it is the first of its kind to use modern versions of organic photovoltaic components.
In the UCLA design, the materials of the system assemble themselves by merely being placed close to each other.
Tolbert said they worked hard in designing the system so that they would not have to work hard in operating it.
The new technology is also greener compared with current designs because its materials can be assembled in water rather than conventional organic substances that are toxic.
Tolbert and her colleagues are now working on incorporating their technology into functioning solar cells.
The University of California, Los Angeles study is published in the journal Science.
Photo: Dominic Alves | Flickr
