Researchers have integrated solar cells into a 'smart' window that can intelligently regulate the transmission of heat while maintaining visible transparency. The smart window, described in the journal Scientific Reports, combines energy saving and generation in a single device.
Most efforts to efficiently utilise solar energy have been focused on improving the efficiency in the conversion and storage using solar cells and large capacity batteries, respectively. However, these cells, which have been used on housetops and wall periphery, could not be integrated into windows that require the material to be transparent. Traditionally designed energy-saving windows, such as electrochromic thermochromic, and gasochromic, typically function by exterior stimuli involving either an electric field, heat stimulus or a gas. It is not possible to alter the optical performance, which involves intelligently passing or blocking solar energy in response to environmental changes, and simultaneously generate electricity. Herein, a novel smart window was designed such that the VO2 films or particles regulate solar infrared radiation and scatter partial light to a solar cell for electricity generation.
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 degree Celcius, the material is insulating and transparent to infrared light, but above 68 degree Celcius it becomes metallic and reflective to infrared light.
Previously, it was a challenge to integrate solar cells that can efficiently harness and store solar energy into windows that require the material to be transparent. In this study, Yanfeng Gao and colleagues from the Chinese Academy of Sciences positioned vanadium oxide films around glass panels to regulate solar infrared radiation in response to environmental temperature and scatter partial light to solar cells.
The researchers say that their device may someday contribute towards reducing energy costs for heating, lighting and cooling buildings.
Source: Chinese Academy of Sciences
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