An international team of researchers from Sweden and China has developed organic photovoltaic cells that convert ambient indoor light into electricity.
Organic solar cell. Image credit: Thor Balkhed.
“Our work indicates great promise for organic solar cells to be widely used in our daily life for powering the internet of things,” said Dr. Feng Gao, a researcher at Linköping University.
As the internet of things expands, it is expected that we will need to have millions of products online, both in public spaces and in homes. Many of these will be the multitude of sensors to detect and measure moisture, particle concentrations, temperature and other parameters.
For this reason, the demand for small and cheap sources of renewable energy is increasing rapidly, in order to reduce the need for frequent and expensive battery replacements.
This is where organic solar cells come in. Not only are they flexible, cheap to manufacture and suitable for manufacture as large surfaces in a printing press, they have one further advantage: the light-absorbing layer consists of a mixture of donor and acceptor materials, which gives considerable flexibility in tuning the solar cells such that they are optimized for different spectra — for light of different wavelengths.
Dr. Gao and colleagues developed a new combination of donor and acceptor materials for use as the active layer in an organic solar cell.
The combination absorbs exactly the wavelengths of light that surround us in our living rooms, at the library or in the supermarket.
The researchers created two versions of an organic solar cell: one with an area of 1 cm2 and the other 4 cm2.
The smaller solar cell was exposed to ambient light at an intensity of 1,000 lux, and the scientists observed that as much as 26.1% of the energy of the light was converted to electricity.
The organic solar cell delivered a high voltage of above 1 V for more than 1,000 hours in ambient light that varied between 200 and 1,000 lux.
The larger solar cell still maintained an energy efficiency of 23%.
“We are confident that the efficiency of organic solar cells will be further improved for ambient light applications in coming years, because there is still a large room for optimization of the materials used in this work,” said Professor Jianhui Hou, from the Chinese Academy of Sciences’ Institute of Chemistry.
The team’s work was published in the journal Nature Energy.
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Yong Cui et al. 2019. Wide-gap non-fullerene acceptor enabling high-performance organic photovoltaic cells for indoor applications. Nature Energy 4: 768-775; doi: 10.1038/s41560-019-0448-5
