How the windows of tomorrow generate electricity – ScienceDaily

Five years on from the Paris Agreement, all eyes are on the world’s progress towards a carbon-free future. An essential part of this goal is the energy transition from fossil fuels to renewable sources such as sun, water, wind and wave energy. Among these, solar energy, as the most reliable and abundant source of energy on earth, has always had the greatest hope in the scientific community. In the last few decades solar cells have become cheaper, more efficient and more environmentally friendly. However, current solar cells tend to be opaque, which prevents their wider use and integration into everyday materials, as they only need to be lined up on rooftops and in remote solar parks.

But what if next-generation solar panels could be integrated into windows, buildings or even cell phone screens? This is the hope of Professor Joondong Kim of the Electrical Engineering Institute at Incheon National University, Korea. In a study recently published in the Journal of Power Sources, he and his colleagues describe their latest invention: a completely transparent solar cell. “The unique properties of transparent photovoltaic cells could have various applications in human technology,” says Prof. Kim.

The idea of ​​transparent solar cells is well known, but this novel application where scientists were able to put this idea into practice is a crucial new finding. At present, the materials that make the solar cell opaque are the semiconductor layers, which are responsible for capturing light and converting it into electricity. Therefore, Prof. Kim and his colleagues examined two potential semiconductor materials that had been identified by previous researchers for their desirable properties.

The first is titanium dioxide (TiO2), a well-known semiconductor that is already widely used to make solar cells. In addition to its excellent electrical properties, TiO2 is also an environmentally friendly and non-toxic material. This material absorbs UV light (part of the light spectrum invisible to the naked eye) and lets through most of the visible light range. The second material that was investigated to make this junction was nickel oxide (NiO), another semiconductor known to have high optical transparency. Since nickel is one of the most foggy elements on earth, and its oxide can be easily made at low industrial temperatures, NiO is also a great material for making environmentally friendly cells.

The solar cell made by the researchers consisted of a glass substrate and a metal oxide electrode on which thin layers of the semiconductors (first TiO2, then NiO) and a final coating of silver nanowires as the other electrode were deposited in the cell. They performed several tests to evaluate the device’s absorption and transmission of light, as well as its effectiveness as a solar cell.

Your results were encouraging; With a power conversion efficiency of 2.1%, the cell performed reasonably well as it only targets a small portion of the light spectrum. The cell also responded very well and worked in low light conditions. In addition, more than 57% of the visible light was transmitted through the cell layers, which gives the cell this transparent aspect. In the last part of their experiment, the researchers showed how their device can be used to drive a small motor. “While this innovative solar cell is still in its infancy, our results strongly suggest that a further improvement in transparent photovoltaics is possible by optimizing the optical and electrical properties of the cell,” suggests Prof. Kim.

After demonstrating the practicality of a transparent solar cell, they hope to further improve its efficiency in the near future. Only more research can tell if they will actually become a reality, but this new technology in every way opens a – literally – window into the future of clean energy.

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Materials provided by Incheon National University. Note: The content can be edited by style and length.

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