Qingdao Energy Institute reveals the aging process and solution of perovskite solution
In the past decade, the technology of perovskite solar cells has developed rapidly, and its latest certified photoelectric conversion efficiency is as high as 25.2%. The efficiency of perovskite solar cells depends largely on the crystalline quality of the perovskite photoactive layer, which is also the primary issue to be considered in the preparation of perovskite thin films by the solution method.
Before preparing the perovskite film by the solution method, a certain temperature and stirring are required to ensure that the precursor is fully dissolved. In the future industrial production process, this process may be longer. Therefore, the composition of the perovskite precursor solution needs to remain stable. For the single system of methylamine lead and iodine, as long as the solution system is sufficiently sealed, the material itself is still very stable. However, when methylamine and formamidine coexist in the solution system, the decay of the solution is particularly obvious. The result is that a fresh solution needs to be configured before each device is made, which not only brings tediousness to the device research work, but also Brought a lot of uncontrollability, has become an important obstacle to restrict the development of perovskite devices.
In response to this problem, Cui Guanglei and Ping Shuping, a researcher from the Qingdao Institute of Bioenergy and Process Research, Chinese Academy of Sciences, recently conducted an in-depth study on the aging process of the perovskite precursor solution. The researchers found that obvious side reactions occurred in the mixed organic cation perovskite solution of methylamine ion and formamidine ion, and found a solution to suppress these side reactions, which proved to improve the stability of the perovskite precursor solution It is the key to further improve battery photoelectric efficiency and enhance device repeatability. The research results were published in Chem.
The researchers used nuclear magnetic resonance technology to track the composition of the solution during the aging process and found that with the extension of time, the composition of methyl iodide and formamidine iodide in the perovskite solution gradually decreased, and some new compounds appeared. It was undiscovered before. They finally determined the structure of the side reaction product and revealed its reaction mechanism. In fact, it is an addition-elimination reaction with formamidine iodide after deprotonation of methylamine iodide. In order to further confirm the accuracy of the conclusion, they synthesized this kind of substance through chemical means, with the same nuclear magnetic signal.
The purpose of the problem was to solve this problem. The researchers introduced triethyl borate into the solution, and used the empty orbit of boron to interact with the iodide ion of methylamine iodide to limit its deprotonation, thus effectively limiting Further addition-elimination reaction with formamidine iodide achieves the purpose of improving the stability of the perovskite precursor solution. Triethyl borate is a commonly used low-boiling solvent. It can completely volatilize during the subsequent film heating process, and will not remain in the perovskite film. This is particularly important for the preparation of high-quality perovskite films.
In addition, the researchers also studied other side reactions that may exist, such as the previously reported solvolysis to form dimethylamine, etc., but such reactions usually occur at very high temperatures. In the conventional process of preparing perovskite films, the side reaction between methylamine and formamidine is the main one, which also explains why it is difficult to completely eliminate the miscellaneous phase in the formamide composite perovskite film.
The research was supported by Shandong Provincial Talent Project, Provincial Outstanding Youth Fund, Innovation Research Institute Cooperation Fund, and National Outstanding Youth Fund.
Figure: Using triethyl borate additives to inhibit side reactions in perovskite solutions.
Besides aluminum nuts,Stainless Steel Nuts,steel nuts, we also offer Nylon Nuts. The nylon nuts are fit for nylon screws. The most popular nylon nuts are nylon hex nuts. We have lots of M3 nylon nuts in stock. Black color is most common. If you need other sizes, please feel free to contact me . We will try our best to support you. If you need special packing service including special package boxes, it is also ok for us. Any questions or demand, please feel free to contact us.
Nylon Nut,Square Nylon Nut,Hexagonal Nylon Nut,Nylon Lock Nut,Nylon Hexagon Nut
Hobby Carbon CNC Technology(Shenzhen) Limited , https://www.hobbycarbon.com