Semi-transparent solar cells that could be added to windows to efficiently harvest energy from indoor light as well as the sun have been developed by an international team led by UCL researchers.

The technology, described in a paper in Advanced Energy Materials, could help to turn buildings into power generators at night and on cloudy days as well as during sunshine.

The researchers engineered solar windows that let in 30 per cent of sunlight (ordinary glass might let in 80 per cent or 90 per cent) while generating a record amount of energy from indoor light as well as efficiently harvesting energy from sunshine.

The team used perovskite which is increasingly used in outdoor solar panels and, unlike traditional silicon-based solar panels, has potential to generate energy from indoor light as its composition can be adjusted to better absorb indoor light’s specific wavelengths.

Senior author Dr Mojtaba Abdi-Jalebi, at the UCL Institute for Materials Discovery, said: “Rooftops are commonly fitted with solar panels but the vast window areas of many modern buildings remain largely untapped as an energy resource.

“The next step is to engineer flexible solar cells that can be applied to curved structures like windows on the Shard or on cars as well as non-rigid surfaces such as clothes or backpacks. We would also like to build solar cells over larger scales than we achieved in this study.”

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