A self-powering smart window that controls the amount of light and reduces heat loss has been developed by scientists.

While windows currently available can shave off 40 per cent of energy costs, they are difficult to install as they require new power supplies.

By applying a new transparent solar cell technology, researchers have developed a different type of smart window that is both cheaper and easier to install - and they could save on energy costs.

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A self powering smart window that controls the amount of light let through and reduces heat or cold has been developed by scientists

HOW DOES IT WORK? The study used organic semiconductors - contorted hexabenzocoronene (cHBC) derivatives - for constructing the solar cells. Its chemical structure can be modified to absorb a narrow range of wavelengths - in this case, near-UV light. The semiconductor molecules were deposited as thin films on glass with the same production methods used by organic light-emitting diode manufacturers. When the solar cell is operational, sunlight excites the cHBC semiconductors to produce electricity. At the same time, the researchers constructed a smart window consisting of electrochromic polymers, which control the tint, and can be operated solely using power produced by the solar cell. When near-UV light from the sun generates an electrical charge in the solar cell, the charge triggers a reaction in the electrochromic window, causing it to change from clear to dark blue. When darkened, the window can block more than 80 per cent of light. Advertisement

The window, which was developed by researchers from Princeton University, uses near-ultraviolet light to generate electricity, which powers chemical reactions that lighten or darken the glass as needed.

When darkened, the window can block more than 80 per cent of light.

Professor Yueh-Lin Loo, lead author of the study, said: 'Sunlight is a mixture of electromagnetic radiation made up of near-UV rays, visible light, and infrared energy, or heat.

'We wanted the smart window to dynamically control the amount of natural light and heat that can come inside, saving on energy cost and making the space more comfortable.'

The smart window controls the transmission of visible light and infrared heat into the building, while the new type of solar cell uses near-UV light to power the system.

Professor Loo added: 'This new technology is actually smart management of the entire spectrum of sunlight.

'Using near-UV light to power these windows means that the solar cells can be transparent and occupy the same footprint of the window without competing for the same spectral range or imposing aesthetic and design constraints.

'Typical solar cells made of silicon are black because they absorb all visible light and some infrared heat - so those would be unsuitable for this application.'

The study used organic semiconductors - contorted hexabenzocoronene (cHBC) derivatives - for constructing the solar cells.

Its chemical structure can be modified to absorb a narrow range of wavelengths - in this case, near-UV light.

The semiconductor molecules were deposited as thin films on glass with the same production methods used by organic light-emitting diode manufacturers

WHAT ELSE COULD SOLAR CELLS BE USED FOR? Professor Loo and Mr Davy have set up Andluca Technologies to explore other applications for the transparent solar cells. They explained that the near-UV solar cell technology can also power internet sensors and other low-power consumer products. Professor Loo said: 'It does not generate enough power for a car, but it can provide auxiliary power for smaller devices, for example, a fan to cool the car while it's parked in the hot sun.' Advertisement

The semiconductor molecules were deposited as thin films on glass with the same production methods used by organic light-emitting diode manufacturers.

When the solar cell is operational, sunlight excites the cHBC semiconductors to produce electricity.

At the same time, the researchers constructed a smart window consisting of electrochromic polymers, which control the tint, and can be operated solely using power produced by the solar cell.

When near-UV light from the sun generates an electrical charge in the solar cell, the charge triggers a reaction in the electrochromic window, causing it to change from clear to dark blue.

Doctoral student Nicholas Davy said the aim was to create a flexible version of the solar-powered smart window system that can be applied to existing windows via lamination.

He said: 'Someone in their house or apartment could take these wireless smart window laminates - which could have a sticky backing that is peeled off - and install them on the interior of their windows.

The smart window controls the transmission of visible light and infrared heat into the building, while the new type of solar cell uses near-UV light to power the system (stock image)

'Then you could control the sunlight passing into your home using an app on your phone, thereby instantly improving energy efficiency, comfort, and privacy.'

Senior research scientist Joseph Berry at the National Renewable Energy Laboratory, commented: 'Integrating the solar cells into the smart windows makes them more attractive for retrofits and you don't have to deal with wiring power.

'And the voltage performance is quite good.

'The voltage they have been able to produce can drive electronic devices directly, which is technologically quite interesting.'

Professor Loo and Mr Davy have set up Andluca Technologies to explore other applications for the transparent solar cells.

They explained that the near-UV solar cell technology can also power internet sensors and other low-power consumer products.

Professor Loo said: 'It does not generate enough power for a car, but it can provide auxiliary power for smaller devices, for example, a fan to cool the car while it's parked in the hot sun.'