The molecule has the unique ability to capture energy from the sun’s rays and release it later as heat.

The technology could both improve the indoor temperature variance of buildings equipped with the film, as well as reducing the energy used for air conditioning or heating.

The developers of the film, who work at Chalmers University of Technology, Sweden, say that when their specially designed molecule is struck by the Sun’s rays it captures photons and simultaneously changes form.

When the Sun stops shining on the window film, the molecules release heat for up to eight hours after the Sun has set.

“The aim is to create a pleasant indoor environment even when the Sun is at its hottest, without consuming any energy or having to shut ourselves behind blinds. Why not make the most of the energy that we get free of charge, instead of trying to fight it?” said chemist Kasper Moth-Poulsen, who is leading the research.

At dawn, when the film has not absorbed any solar energy, it appears yellow or orange since these colours are the opposite of blue and green, which is the light spectrum that the researchers have chosen to capture from the Sun.

When the molecule captures solar energy and is isomerised, it loses its colour and becomes entirely transparent. As long as the Sun is shining on the film it captures energy, which means that not as much heat penetrates through the film and into the room.

At dusk, when there is less sunlight, heat starts to be released from the film and it gradually returns to its yellow shade and is ready to capture sunlight again the following day.

“For example, airports and office complexes should be able to reduce their energy consumption while also creating a more pleasant climate with our film, since the current heating and cooling systems often do not keep up with rapid temperature fluctuations,” said Moth-Poulsen.

The molecule is part of a concept the research team calls MOST, which stands for Molecular Solar Thermal Storage.

Previously, the team presented an energy system for houses based on the same molecule. In that case – after the solar energy had been captured by the molecule – it could be stored for an extended period, such as from summer to winter, and then used to heat an entire house.

The researchers realised that they could shorten the step to application by optimising the molecule for a window film as well, which would also create better conditions for the slightly more complex energy system for houses.

What the researchers still have to do is to increase the concentration of the molecule in the film whilst also retaining the film’s properties and lower the cost. Moth-Poulsen believes that both are achievable in the near future.

The molecule has the unique ability to capture energy from the sun’s rays and release it later as heat.

The technology could both improve the indoor temperature variance of buildings equipped with the film, as well as reducing the energy used for air conditioning or heating.

The developers of the film, who work at Chalmers University of Technology, Sweden, say that when their specially designed molecule is struck by the Sun’s rays it captures photons and simultaneously changes form.

When the Sun stops shining on the window film, the molecules release heat for up to eight hours after the Sun has set.

“The aim is to create a pleasant indoor environment even when the Sun is at its hottest, without consuming any energy or having to shut ourselves behind blinds. Why not make the most of the energy that we get free of charge, instead of trying to fight it?” said chemist Kasper Moth-Poulsen, who is leading the research.

At dawn, when the film has not absorbed any solar energy, it appears yellow or orange since these colours are the opposite of blue and green, which is the light spectrum that the researchers have chosen to capture from the Sun.

When the molecule captures solar energy and is isomerised, it loses its colour and becomes entirely transparent. As long as the Sun is shining on the film it captures energy, which means that not as much heat penetrates through the film and into the room.

At dusk, when there is less sunlight, heat starts to be released from the film and it gradually returns to its yellow shade and is ready to capture sunlight again the following day.

“For example, airports and office complexes should be able to reduce their energy consumption while also creating a more pleasant climate with our film, since the current heating and cooling systems often do not keep up with rapid temperature fluctuations,” said Moth-Poulsen.

The molecule is part of a concept the research team calls MOST, which stands for Molecular Solar Thermal Storage.

Previously, the team presented an energy system for houses based on the same molecule. In that case – after the solar energy had been captured by the molecule – it could be stored for an extended period, such as from summer to winter, and then used to heat an entire house.

The researchers realised that they could shorten the step to application by optimising the molecule for a window film as well, which would also create better conditions for the slightly more complex energy system for houses.

What the researchers still have to do is to increase the concentration of the molecule in the film whilst also retaining the film’s properties and lower the cost. Moth-Poulsen believes that both are achievable in the near future.