2022.02.04
Professor Yeonjin Yi (Department of Physics) research team has identified the principle of degradation of black lin, the biggest stumbling block in black lin applications, and has proposed a fundamental solution.
Black phosphorus is a substance consisting only of phosphorus(P) elements with a unique atomic arrangement. Like graphene, it is capable of two-dimensional peeling and has very good electrical and optical properties. Unlike Graphene, which is difficult to control the current, Blacklin has the advantage of being able to control the current through band gap and adjustment, making the electronic device easy. However, due to its instability, which is vulnerable to oxygen and moisture in the air, physical properties research and applications are difficult.(*Bandgap: Energy level difference to determine electrical conductivity)
The research team determined that the key physical amount that determines the performance degradation of black lin is the electron density, and it can be controlled to prevent the performance degradation. Electron density refers to the amount of electrons present at a specific energy in a substance.
The band gap changes with thickness, and the researchers expected this unique physical property to be deeply associated with poor performance. Therefore, the change in the surface properties of black phosphorus in reaction with oxygen and moisture in the air was accurately measured with an atomic force microscope.
As a result, contrary to common expectations, more than eight layers of thick black lin caused faster performance degradation than two layers of thin black lin. The research team has developed a theoretical model that can explain this. According to this research model, the thicker the black phosphorus, the smaller the band gap and the greater the electron density, thereby accelerating the chemical reaction with oxygen moisture.
Professor Yeonjin Yi explained the significance of the study:”The theoretical model that explains the cause of the performance decline is not limited to Black lin, but can be applied to other two-dimensional semiconductors." In addition, “In the future, we plan to control the surface electron density of the black lin to produce an electronic device that improves not only the electrical properties but also the stability,”said a follow-up study plan.
On the other hand, this research was conducted in collaboration with Professor Kim Tae-kyung(Hankuk University of Foreign Studies)and supported by the Korea Research Foundation Basic Research Project(Leading Research Center Basic Research Mid-research Leader Research)of the Ministry of Education, Science, Technology, Information and Communication. The results of the study were selected as an internal cover paper of Angewandte Chemie and published in Issue 12(March 11), 2019.