High-efficiency solar cells that can withstand the heat of a steamer and high humidity are emerging [Now in Science]

A perovskite solar cell that can last 1,000 hours even in a steamer-like environment has been developed. A protective film was applied to the cell.



Professor Dong-Seok Kim's team at the Carbon Neutral Graduate School of Ulsan National Institute of Science and Technology (UNIST) and Professor Tae-Kyung Lee's team at Gyeongsang National University developed a heat-resistant perovskite solar cell that can withstand high-temperature processes by applying a protective film to the solar cell.



This cell showed a high initial efficiency of 25.56%. It maintained more than 85% of the initial efficiency even after operating for 1,000 hours at 85℃ and 85% relative humidity



. Photoelectric conversion efficiency of perovskite solar cell cells and modules made with added ethylene carbonate. The cell using ethylene carbonate (target) showed a higher photoelectric conversion efficiency (PCE) than the cell using tBP (control). [Photo = UNIST]



Perovskite solar cells are next-generation cells that theoretically convert sunlight into electricity more efficiently and cost less than commercial silicon cells. In the laboratory, they have already achieved an efficiency of 27%.



One of the reasons why these cells, which surpass silicon cells, have not reached the commercialization stage is heat resistance. Since the cells are operated outdoors for long periods of time, they must be wrapped in a film to protect them from moisture and oxygen. Unlike silicon cells, they cannot withstand process temperatures as high as 110℃.



The research team created a heat-resistant perovskite cell using a substance called ethylene carbonate instead of tBP (4-tert-Butylpyridine). tBP is an additive added to the hole transport layer of a solar cell.



This substance increases efficiency, but lowers the glass transition temperature of the hole transport layer to below 80℃, preventing the cell from withstanding high temperatures. The glass transition is a phenomenon in which the hole transport layer approaches a liquid state.



The cell made of ethylene carbonate recorded a photovoltaic conversion efficiency (PCE) of 25.56%. This is the world's highest efficiency among cells that do not use tBP. In addition, there was almost no decrease in efficiency even when it went through the encapsulation process of applying a protective film. When



the encapsulated cell was tested under international standard conditions of 85℃ and 85% relative humidity, it showed excellent durability, maintaining an efficiency of 21.7% even after 1,000 hours. The glass transition temperature of the hole transport layer also rose to 125℃.



This cell showed a high efficiency of 22.14% even when manufactured as a module with an area of ​​100cm². This is because ethylene carbonate can evenly dissolve the lithium bismide (LiTFSI) doping agent as well as tBP.



When LiTFSI is well doped, the charge transfer performance of the hole transport layer is improved, increasing the efficiency of the entire solar cell.



Professor Kim Dong-seok explained, "Through this research, we have developed a solar cell hole-transport layer system that can secure stability in high-temperature and high-humidity environments while maintaining high efficiency," and "This is a decisive step forward for the commercialization of perovskite solar cells."



The research results (paper title: Damp-heat stable and efficient perovskite solar cells and mini-modules with tBP-free hole-transporting layer) were published on April 7 in the international academic journal in the field of eco-friendly energy, Energy & Environmental Science.





https://www.inews24.com/view/blogger/1832195

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