Perovskite is a type of compound with the same crystal structure. Due to its low cost, flexibility and relatively easy manufacturing process, it has received extensive attention as a potential new solar cell material. However, there are still many unknowns about their structural details and the effect of replacing different metals or other elements in the material. Traditional solar cells made of silicon must be processed at temperatures above 1400 degrees Celsius, and the use of expensive equipment limits their potential for expanding production. In contrast, perovskites can be processed in liquid solutions as low as 100 degrees, using inexpensive equipment. More importantly, perovskite can be deposited on a variety of substrates, including flexible plastics, which allows perovskite to have a variety of new uses, which are on thicker, harder silicon wafers It is impossible. Now, the researchers have been able to explain a key aspect of the perovskite behavior, which is made from different formulations: among some additives, there is a "sweet spot" on which to add More perovskite will improve performance, while adding more perovskite will start to decrease performance. The discovery was published in the journal Science, by former postdoctoral fellows of the Massachusetts Institute of Technology, Juan-Pablo Colia-Baena, MIT professors Tonio Bunasi and Monge Bavandi And 18 professors from MIT, UC San Diego and other institutions. Perovskite is a type of compound with a three-part crystal structure. Each component can be composed of any of many different elements or compounds, resulting in a very wide range of possible formulas. Buonassisi likens the design of a new perovskite to ordering from the menu, choosing one (or more) from each column a, B, and (as usual) X. "You can mix and match," he said, but so far, all changes can only be studied through trial and error, because the researchers do not have a basic understanding of what is happening in the material. Earlier, a research team at the Ecole Polytechnique Federale de Lausanne in Switzerland found that the addition of certain alkali metals to the perovskite mixture can improve the efficiency of this material in converting solar energy into electricity, from about 19% To about 22%. Coria Baena also participated in this study. However, this improvement was not explained at the time, and it was not known exactly what these metals did in the compound. "We don't know much about how microstructure affects performance," Buonassisi said. Now, detailed mapping using high-resolution synchrotron nanox-ray fluorescence measurement technology reveals the details of this process, providing potential clues to further improve the performance of this material. It turns out that adding alkali metals such as cesium or rubidium to perovskite compounds can help other ingredients mix together more smoothly. As the team described, these additives help to "homogenize" the mixture, making it easier to conduct electricity, thereby improving its efficiency as a solar cell. However, they found that this only works to a certain extent. Above a certain concentration, these added metals will gather together to form areas that interfere with the conductivity of the material, and to some extent offset the initial advantage. They found that between these two, any given formulation of these complex compounds is the best point to provide the best performance. Says: "This is a big discovery Correa-Baena, who became an assistant professor in January at Georgia Tech's Materials Science and Engineering, the researchers found that the collaborators who worked three years later at MIT and UC San Diego are "When you add these alkali metals and the performance improves. "They can directly observe the changes in the composition of the material, revealing the offset effect of homogenization and agglomeration." Correa-Baena said: "Based on these findings, we now know that we should study similar systems, such as adding alkali metals or other metals, or changing other parts of the formula." Although perovskites have great advantages over traditional silicon solar cells, especially in terms of the low cost of establishing factories to produce perovskites, they still need further work to improve overall efficiency and lifespan, which is far behind For silicon batteries. Although researchers have clarified the structural changes that occur when perovskite materials are added with different metals, and the resulting performance changes, "we still don't understand the chemical principle behind this," corria-baena said. This is the ongoing research topic of the group. According to Correa-Baena data, in theory, the maximum efficiency of these perovskite solar cells is about 31%, and the best performance so far is about 23%, so there is still much room for improvement. Although it may take years for perovskite to fully realize its potential, at least two companies are already building production lines, and they hope to begin selling the first modules around next year. Some of them are small, transparent, colored solar cells designed for integration on the facade of the building. "This has already happened," Correa-Baena said, "but there is a lot of work to be done to make these more durable." Buonassisi said that once large-scale manufacturability, efficiency and durability issues are resolved, perovskite may become a major player in the renewable energy industry. He said: "If they successfully manufacture sustainable and efficient modules while keeping manufacturing costs low, it may change the rules of the game." "This will make solar expansion much faster than we have seen." Perovskite solar cells "are now the main candidates for commercialization. Therefore, as done in this work, providing deeper insights will help future development," University of Fribourg, Switzerland Michael Saliba, senior researcher in physical physics, said. He did not participate in this study. Saliba added: "This is a great job, which reveals some of the most researched materials. The combination of new technologies based on synchrotrons and new materials engineering is of the highest quality and is worth being in such an advanced journal Publish. He added that work in this area is "progressing rapidly." Therefore, having more detailed knowledge will be very important for solving future engineering challenges. In addition to researchers from the Massachusetts Institute of Technology and the University of California, San Diego, this research also includes researchers from Purdue University and Argonne National Laboratory. The research was supported by the US Department of Energy, the National Science Foundation, Skolkovo Institute of Science and Technology, and the California Energy Commission. 12 Volt Dc Appliances,Dc Appliances ,Dc Appliances For Off-Grid,5 In.Series Led Downlight Wuxi Shengda Yukun Energy Development co.,Ltd , https://www.xlite-solarlight.com
Solar cells made of perovskite have a promising future, partly because they can be easily made on flexible substrates, like this experimental cell. Image: Ken Richardson