Until now, doped polymer inks have been largely confined to conducting positive electrons. The most common of these ‘p-type’ conductors is called PEDOT:PSS, which exhibits high electrical conductivity, good ambient stability, and is widely commercially available. The new ink, known as BBL:PEI, is an ‘n-type’ polymer capable of conducting negative charged electrons, which can act as a negative equivalent to PEDOT:PSS.
Developed by researchers in Sweden, the US and South Korea, the new material is important as many electronics require both ‘n-type’ and ‘p-type’ conductivity to function. The work is described in detail in Nature Communications.
"This is a major advance that makes the next generation of printed electronic devices possible,” said says Simone Fabiano, senior lecturer in the Department of Science and Technology at Sweden’s Linköping University.
“The lack of a suitable n-type polymer has been like walking on one leg when designing functional electronic devices. We can now provide the second leg.”
The new n-type material comes in the form of ink with ethanol as the solvent. The ink can be deposited by spraying the solution onto a surface, making organic electronic devices easier and cheaper to manufacture. The researchers claim the ink is also more eco-friendly than many other n-type organic conductors currently under development, which often contain harmful solvents. According to Fabiano, the technology is ready to be used in applications now.
"Large-scale production is already feasible, and we are thrilled to have come so far in a relatively short time,” he said.
“We expect BBL:PEI to have the same impact as PEDOT:PSS. At the same time, much remains to be done to adapt the ink to various technologies, and we need to learn more about the material.”