Using nanotechnology, researchers from the University of Gothenburg created plasmonic nanoantennas which strongly absorb light and heat the surface they're placed on (which could be anything, although they're most suited to glass). Even when a pane of glass is covered in the nanoantennas it remains transparent and colorless, and almost completely preserves the color spectrum of sunlight.
"We've developed a surprisingly simple, cheap, and effective way to transform regular glass windows into solar-powered heat-screens that could significantly change the thermal balance of living and working spaces, especially if one thinks of the ever increasing amount of huge glass surfaces used in modern architecture," lead researcher Alexandre Dmitriev told Phys.org. He added that while the technology's prominent application is reducing heating costs, the nature of the nanoantennas means it could have uses in other areas, such as radiative cooling and solar-powered thermal isolation. The team is now working on achieving even larger temperature increases through the absorption of ultraviolet and near-infrared radiation, so it might not be long until the desk by the window is the prime office spot, even on chilly days.