Scientists are coming up with some great solar cell ideas that don’t require the sun! Recently we reported on the anti-solar panel that generates electricity in the dark of night. Now, we’re going to introduce you to indoor organic solar cells that have been optimized to convert ambient indoor light to electricity.
That’s right, the light from the lightbulb can generate electricity to power itself. Well, not quite yet… the power the cells produce is still quite low. For now, it is just enough to feed the millions of products that the internet of things (IoT) will bring online – which is exactly what the Swedish and Chinese scientists that created them had in mind.
Realizing that the future brings an expansion of the IoT, the scientists expect we will need to have millions of products online, both in public spaces and in homes. For example, sensors that detect and measure moisture, particle concentrations, temperature, and other parameters, to name a (very) few. All of these low-energy consuming devices will require small and cheap sources of renewable energy. The idea of having to be frequently replacing batteries for all these things seems absurd and extremely inconvenient – which is where the organic solar cells step in.
The cells are flexible, cheap to manufacture, and suitable to manufacture as large surfaces in a printing press. In addition (and here’s the feature that makes them unique), the light-absorbing layer consists of a mixture of donor and acceptor materials – this gives considerable flexibility in tuning the solar cells such that they are optimized for different spectra (for light of different wavelengths).
The development of this new combination of donor and acceptor materials was a collaboration between researchers in Beijing, China, led by Jianhui Hou, and Linköping, Sweden, led by Feng Gao. The active layer in an organic solar cell is a carefully determined composition of the materials. They found this combination absorbs exactly the wavelengths of light that surround us in our living rooms, at the library, and in the supermarket. The research has been published in the journal Nature Energy.
In the article, they describe two variants of an organic solar cell where one variant has an area of 1 cm² and the other 4 cm². The smaller solar cell that was exposed to ambient light at an intensity of 1000 lux was able to convert as much as 26.1% of the energy of the light into electricity. It managed to deliver a voltage above 1V for more than 1000 hours in ambient light that varied between 200 and 1000 lux. The larger solar cell was not as strong but still good, maintaining an energy efficiency of 23%.
Gao, senior lecturer in the Division of Biomolecular and Organic Electronics at Linköping University, said:
This work indicates great promise for organic solar cells to be widely used in our daily life for powering the internet of things.
Hou, professor at the Institute of Chemistry, Chinese Academy of Sciences, added:
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.
This work is not new however, it’s a continuation of research that has been going on at Linköping University, under the leadership of Olle Inganäs (now professor emeritus) who has been for many years a world-leader in the field of organic solar cells. Their focus now is on commercializing solar cells for indoor use.
