Solar revolution heads indoors with organic cells that feed off ambient light

17 Sep 2019

The organic solar cell. Image: Thor Balkhed

The solar revolution is heading indoors after researchers revealed organic solar cells that can turn ambient indoor light into electricity.

With aims of powering the internet of things (IoT) in the home using renewable electricity, researchers from Sweden and China have teamed up to develop a potentially game-changing organic solar cell.

Writing in Nature Energy, the scientists from Linköping University and the Chinese Academy of Sciences said these solar cells are optimised to convert ambient indoor light into electricity. While in low amounts, it should be enough to power millions of IoT products for the home market.

Increasing demand for devices such as smart speakers has also increased the demand for small and cheap sources of renewable energy, as manufacturers try to find ways to do away with expensive and environmentally damaging battery replacements.

The researchers said these new organic solar cells are flexible, cheap to manufacture and suitable for large surfaces. Additionally, the light-absorbing layer consists of a mixture of donor and acceptor materials. This combination is capable of absorbing the wavelengths of light that surround us in our living rooms, at the library and in the supermarket.

‘Room for optimisation’

Two variants of the solar cell have been revealed: one with an area of 1 sq cm and the other being 4 sq cm. When exposed to ambient light with an intensity of 1,000 lux, the smaller cell converted 26.1pc of light into electricity and delivered 1V for more than 1,000 hours. The larger cell was slightly less efficient at 23pc.

“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 optimisation of the materials used in this work,” said researcher Jianhui Hou.

The news follows another recent substantial breakthrough in solar cell design revealed by a team from the University of Warwick. Its organic solar cell design can be applied to curved surfaces, such as the body of a car, challenging conventional thinking about one of the key components of the design of these cells.

Colm Gorey was a senior journalist with Silicon Republic