Writer: H M Remii

The rainbow-colored soap bubbles under the sun always paint a dreamy, unrealistic, and airy-fairy picture. Yet, the scientists from King Abdullah University of Science and Technology (KAUST), Saudi Arabia, have used these fragile surfaces to demonstrate their groundbreaking innovation. They have invented an ultrathin solar cell that is so light that it can sit on the soap bubble surface. Yes, for real.

Indium is a toxic and expensive metal, which is a necessary element to produce thin-film solar cells. Thin-film solar cells, or what we call the CIGS (copper indium gallium selenide) solar cells, are the third generation of photovoltaic cells. They have been proven to have high power generation efficiency of up to 20.3% with just a tiny cell. When the cells are put together as a module, the efficiency can still reach 14%. Yet, because of the high costs of the rare materials and complex production processes, scientists have been working hard to find alternatives to make highly-efficient-low-budget thin-film solar cells.

The researchers from KAUST made a breakthrough. They have developed a transparent conductive polymer called PEDOT: PSS. A layer of organic photovoltaic material is in the middle of the polymer. The solar cells can work indium-free and be inkjet-printed, while the structure is thin and light enough to be carried on soap bubble surfaces.

Inkjet printing is a science on its own. The scientists need to formulate functional inks for each layer of the solar cell architectures. They also need to overcome the intermolecular force within the cartridge and the ink to let the tiny nozzle eject the very fine ink droplets one by one before they go for the drying stage and other processes to finish the entire production.

These inkjet-printed ultrathin solar cells are coated with waterproof parylene, which can prevent damage from the weather. In the glass plate tests, the researchers found that the inkjet-printed solar cells’ light-electric power conversion efficiency is 4.73%, which is not high. However, the researchers believe that this new technology has its competitive advantages: with the support from computers, inkjet printing can diversify the design of solar cells because the inks can be printed on specific places. So, the ultrathin solar cells can flexibly be made or applied to various devices, skipping the molding process, which saves materials and costs.

The size of batteries is very important to some devices, such as miniaturized sensors, wearable electronics, electronic skins, sensors for flying devices, and biosensors. The toxic-free inkjet-printed solar cell, with its ultrathin and superlight structure, is the perfect power solution for the mentioned devices. Let’s hope scientists can further advance this technology, especially its power generation efficiency, to broaden its application.

Story Source:
https://technews.tw/2020/09/03/inkjet-printed-solar/
https://baike.baidu.hk/item/%E9%8A%85%E9%8A%A6%E9%8E%B5%E7%A1%92/3558514
https://discovery.kaust.edu.sa/en/article/1016/thin-skinned-solar-panels-printed-with-inkjet
https://newatlas.com/energy/inkjet-printed-ultrathin-solar-cells/
https://onlinelibrary.wiley.com/doi/epdf/10.1002/admt.202000226

Image Source:
https://discovery.kaust.edu.sa/en/article/1016/thin-skinned-solar-panels-printed-with-inkjet