A stable high-conductivity polymer ink has the potential to lead to innovative printed electronics with high energy efficiency, researchers claim.
Electrically conducting polymers have led to flexible and lightweight electronic components including organic biosensors, solar cells, light-emitting diodes, transistors, and batteries.
The electrical properties of the conducting polymers can be tuned via ‘doping’, a process in which dopant molecules are added to the polymer to change its properties.
The doped polymer can conduct electricity via electrons (an n-type conductor), or positively charged holes (a p-type conductor). The most commonly used conducting polymer is the p-type conductor PEDOT:PSS, which has high electrical conductivity, excellent ambient stability, and commercial availability as an aqueous dispersion. According to Linköping University in Sweden, a number of electronic devices require a p-type/ n-type combination to function but there is no n-type equivalent to PEDOT:PSS.
Researchers at Linköping, together with colleagues in the US and South Korea, have now developed a conductive n-type polymer ink – BBL:PEI – that is said to be stable in air and at high temperatures. The team’s findings are published in Nature Communications.
“This is a major advance that makes the next generation of printed electronic devices possible. 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”, said Simone Fabiano, senior lecturer in the Department of Science and Technology at Linköping University.
“Everything possible with PEDOT:PSS is also possible with our new polymer,” added Chi-Yuan Yang, a postdoc at Linköping University and one of the principal authors of the paper. “The combination of PEDOT:PSS and BBL:PEI opens new possibilities for the development of stable and efficient electronic circuits.”
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 simpler and more economical to manufacture.
“Large-scale production is already feasible, and we are thrilled to have come so far in a relatively short time,” Fabiano said in a statement. “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.”