<p>Scientists have developed solar- powered smart windows with tunable glazing that can control the heat and light inside a home, saving up to 40 per cent in an average building's energy costs.<br /><br />The system developed by researchers at Princeton University in the US features solar cells that selectively absorb near-ultraviolet (UV) light, so the windows are completely self-powered, inexpensive and easy to apply to existing windows.<br /><br />"Sunlight is a mixture of electromagnetic radiation made up of near-UV rays, visible light, and infrared energy, or heat," said Yueh-Lin Loo, from Princeton.<br /><br />"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," said Loo.<br /><br />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.<br /><br />"This new technology is actually smart management of the entire spectrum of sunlight," said Loo.<br /><br />Since near-UV light is invisible to the human eye, the researchers set out to harness it for the electrical energy needed to activate the tinting technology.<br /><br />"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," Loo said.<br /><br />In the study published in the journal Nature Energy, the researchers described how they used organic semiconductors - contorted hexabenzocoronene (cHBC) derivatives - for constructing the solar cells.<br /><br />They chose the material because its chemical structure could be modified to absorb a narrow range of wavelengths - in this case, near-UV light.<br /><br />To construct the solar cell, the semiconductor molecules are deposited as thin films on glass with the same production methods used by organic light-emitting diode manufacturers.<br /><br />When the solar cell is operational, sunlight excites the cHBC semiconductors to produce electricity.<br /><br />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.<br /><br />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.<br /><br />When darkened, the window can block more than 80 per cent of light.<br /><br /></p>
<p>Scientists have developed solar- powered smart windows with tunable glazing that can control the heat and light inside a home, saving up to 40 per cent in an average building's energy costs.<br /><br />The system developed by researchers at Princeton University in the US features solar cells that selectively absorb near-ultraviolet (UV) light, so the windows are completely self-powered, inexpensive and easy to apply to existing windows.<br /><br />"Sunlight is a mixture of electromagnetic radiation made up of near-UV rays, visible light, and infrared energy, or heat," said Yueh-Lin Loo, from Princeton.<br /><br />"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," said Loo.<br /><br />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.<br /><br />"This new technology is actually smart management of the entire spectrum of sunlight," said Loo.<br /><br />Since near-UV light is invisible to the human eye, the researchers set out to harness it for the electrical energy needed to activate the tinting technology.<br /><br />"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," Loo said.<br /><br />In the study published in the journal Nature Energy, the researchers described how they used organic semiconductors - contorted hexabenzocoronene (cHBC) derivatives - for constructing the solar cells.<br /><br />They chose the material because its chemical structure could be modified to absorb a narrow range of wavelengths - in this case, near-UV light.<br /><br />To construct the solar cell, the semiconductor molecules are deposited as thin films on glass with the same production methods used by organic light-emitting diode manufacturers.<br /><br />When the solar cell is operational, sunlight excites the cHBC semiconductors to produce electricity.<br /><br />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.<br /><br />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.<br /><br />When darkened, the window can block more than 80 per cent of light.<br /><br /></p>