Atomically thin materials known as monolayer semiconductors have been a hot topic in the scientific community and could be used in developments such as transparent and flexible LED displays and ultra-efficient solar cells, but the problem is these materials are riddled with defects.
A team of researchers discovered a simple way to solve this problem using an organic superacid, the University of California at Berkeley reported. The chemical treatment led to a 100-fold increase in the material's photoluminescence quantum yield (the amount of light generated by the material versus the amount of energy put in) and a better quality material. The findings could allow for the practical application of monolayer materials in optoelectronic devices and high-performance transistors.
"Traditionally, the thinner the material, the more sensitive it is to defects," said principal investigator Ali Javey, UC Berkeley professor of electrical engineering and computer sciences and a faculty scientist at Berkeley Lab. "This study presents the first demonstration of an optoelectronically perfect monolayer, which previously had been unheard of in a material this thin."
Superacids are known to "give" protons to other materials in an effect called protonation, which can fill in missing atoms at the sites of defects. The ability to fix these defects is especially important for the development of transistors. Defects more dramatically inhibit these devices' performances because of the fact that they are usually extremely small and thin.
"The defect-free monolayers developed here could solve this problem in addition to allowing for new types of low-energy switches," Javey said.
The findings were published in a recent edition of the journal Science.