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Turn your windows into solar panels? The idea is perhaps not so absurd, according to the research of a group from the University of Tohoku (Japan). They have succeeded in creating photovoltaic cells using materials that achieve 79% transparency, offering numerous application possibilities: windows, car windshields, or even on human skin, according to the researchers.
“Scientists have been trying to develop transparent solar cells for a long time, but so far there have been no suitable materials,” Tohoku University said in a statement. Thus, it is the materials that form the cornerstone of their research. The achievements were described in the journal Nature.
Theoretically, these new transparent photovoltaic cells could be placed on many surfaces: windows, car windshields, or even, the university emphasizes … on human skin.
To make these cells, the researchers used indium tin oxide. It is one of the most widely used transparent conducting oxides. They also used tungsten disulfide. “They coated various thin metals with indium tin oxide (ITO) and inserted a thin layer of tungsten oxide between the coated ITO and tungsten disulfide,” the university said.
However, transparency is not the only advantage of these new photovoltaic cells. They are also, according to scientists, extremely efficient: “The way we formed the solar cell resulted in a power conversion efficiency of more than 1000 times higher than that of a device using a conventional ITO electrode,” notes Toshiaki Kato. author of the article and associate professor at the Graduate School of Engineering, Tohoku University.
Image of a highly transparent solar cell made from 2D atomic foil. © Toshiaki Kato
From photovoltaic cell to solar panel
The university highlights the inconspicuous side of new solar panels that this research could bring. But of course, this is not just a matter of aesthetics. Indeed, there is currently a lively debate about the use of surfaces needed to generate photovoltaic energy. In France, “if today the capacity installed in solar energy is distributed equally to land and buildings, the dynamics are clearly in favor of installations on land. First, because installation on an existing structure, paradoxically, still costs too much or brings less profit than on the ground,” we can read in the Reporterre review on this issue. So new materials that are easier to integrate into buildings could make a difference.
The team is now working on how these photovoltaic cells can be integrated into real solar panels. Indeed, even if a solar cell is functional on an individual level, this does not mean that we can multiply them while maintaining their efficiency. “It is necessary to choose an appropriate architectural design for scaling solar cells,” the scientists explain. They have already started digging into it and shared some of the advances in it: “We have found the appropriate design changes needed to prevent the unexpected voltage drop that accompanies the increase in device area,” says Toshiaki Kato.