Solar cells have been integrated into a ‘smart’ window that can intelligently regulate the transmission of heat (in the form of near-infrared light) while maintaining visible transparency. The smart window, described in Scientific Reports this week, combines energy saving and generation in a single device.
Vanadium oxide (VO2) is an attractive material for the fabrication of smart windows because of the reversible, temperature-dependent phase transitions it undergoes. Below a critical temperature of 68 oC, the material is insulating and transparent to infrared light, but above 68 oC it becomes metallic and reflective to infrared light. Integrating solar cells that can efficiently harness and store solar energy into windows that require the material to be transparent has remained challenging.
Yanfeng Gao and colleagues designed a smart window in which VO2 films regulate solar infrared radiation in response to environmental temperature, and scatter partial light to solar cells positioned around the glass panel. The device could potentially contribute towards reducing the energy costs for heating, lighting and cooling buildings, the team speculate.