Researchers at the Institute for Research in Electronics and Applied Physics at the University of Maryland have designed smart windows that can both harness solar energy and switch between allowing and blocking light. The NASA-funded study, published in ACS Photonics, describes a technology that powers itself and stores energy for other devices.
The window uses a polymer matrix containing microdroplets of liquid crystals and an amorphous silicon layer, similar to those found in solar cells, sandwiched between glass panes. When the window is turned off, the liquid crystals disperse light, making the glass opaque while the silicon absorbs solar energy for later use. When turned on, the liquid crystals adjust to let light pass through.
According to the researchers, the window remains opaque from certain viewing angles even when turned on. This allows some light to be absorbed while the window is simultaneously admitting light, which the team says maximizes energy absorption and efficiency.
The ability to switch the windows on and off gives users control over temperature management and privacy. Existing solar-powered smart windows automatically decide when to block or allow light, according to the source. The new design eliminates the need for curtains or blinds, the researchers say.
The study notes that the technology could also be adapted for other optoelectronic devices. The source quotes a statement that "the ability to electrically control transparency and scattering of light is important for many optoelectronic devices; however, such versatility usually comes with additional unwanted optical absorption and power loss."
The solar smart windows require very little energy for self-powering—as little as 13 nanometers of amorphous silicon, according to the study. The research was funded by NASA and published in ACS Photonics.
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