Research from China All solar cells will be paper-thin and flexible in the future

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Thin solar cells as flexible as paper – that's the latest innovation from the laboratories of Chinese scientists in Shanghai. And this isn't about expensive custom-made designs.

The conventional "c-SI" solar cells, currently dominating the market for large solar farms at 95 percent, could potentially be manufactured as thin as paper and equally flexible in the future.
 Researchers from the Shanghai Institute of Microsystem and Information Technology (SIMIT) have achieved recognition for their innovative technology, earning a feature in the prestigious scientific journal "Nature." The introduction to the paper notes that there had been no progress in this direction for 50 years due to the rigidity of solar cells—until now. 
In the near future, solar cells could be made "foldable" for a variety of applications in space, in the realm of consumer goods known as "wearables," or even for portable energy storage.

Solar cells flutter in the wind like a sail – without breaking

The crystalline silicon solar cell that has been developed is only 60 micrometers thick, as thin as paper, yet it has a bending radius of approximately eight millimeters. It can be folded or flutter in the wind like a sail without breaking.

We replaced the sharp V-grooves with smoother U-grooves, effectively distributing the bending stress and suppressing the tendency to break.

Di Zengfeng, co-author of the study

The team began filming ordinary silicon solar cells, commonly used in photovoltaic ground stations, with a high-speed camera as they broke. In doing so, they discovered that the initial cracks always formed in a "V-shaped groove" at the edge of the silicon wafers. 
Addressing this vulnerability, the researchers stated, "We replaced the sharp V-grooves with smoother U-grooves, effectively distributing the bending stress and suppressing the tendency to break," quoting Di Zengfeng, one of the co-authors of the study, as reported by the South China Morning Post.

The efficiency of energy conversion is not compromised

The new manufacturing technique is only applied to the edges of the wafers, according to the researchers, which ensures that the efficiency of energy conversion is not compromised. This addresses the typical drawbacks of other previously developed "flexible solar cells" made of amorphous silicon, cadmium telluride, organic, and perovskite materials. 
While these other materials may be flexible, the Chinese researchers note that they have low energy efficiency and, as a result, have not been suitable for many commercial scenarios. In contrast, the new invention from Shanghai opens up "new opportunities in sectors such as portable consumer electronics, mobile communication, integrated photovoltaics in architecture, mobile energy supply for vehicles, or in space," it was stated.

Silicon solar cells: highly efficient, lightweight, and flexible

The current results of the experiments, including initial stress tests in Antarctica, demonstrate that they are "highly efficient, lightweight, and flexible silicon solar cells," as stated on the SIMIT website.

During extreme stress tests simulating the fluttering of thin solar wafers in hurricane-like winds, the researchers report that the new solar cells only lost about three percent of their performance after 20 minutes. Apparently, series production is conceivable. However, the scientists still recommend "further in-situ tests." 
With the study published in "Nature," they present a "morphological manufacturing process for the fabrication of foldable crystalline silicon wafers (c-SI) for the commercial mass production of solar cells with remarkable efficiency," write the authors.

Numerous applications are conceivable, from backpacks to sailboats

Possible scenarios where such foldable solar cells could be utilized range from backpacks and tents to the roofs of electric cars, sailboats, airplanes, and research balloons, according to the researchers. They also envision their utility in powering mobile phones and similar devices, as well as generating solar electricity in private households. 
Another advantage of foldable crystalline silicon (c-SI) solar cells is that their production generates much fewer highly toxic waste compared to the manufacturing of conventional flexible cells. Additionally, the process used to round the edges may not only be relevant to photovoltaics but could also be of interest to designers of other flexible electronic devices, noted the researchers from Shanghai.