At Linköping University, Sweden, scientists have designed a stable, highly conductive polymer ink. The breakthrough opens the door for novel printed electronics with high energy efficiency.
The study findings have been published in the Nature Communications journal.
Electrically conducting polymers have enabled the growth of lightweight and flexible electronic components like batteries, transistors, light-emitting diodes, solar cells, and organic biosensors.
The electrical properties of such polymers can be tweaked with the help of a technique called “doping.” This technique involves adding several dopant molecules to the polymer to alter its properties. Based on the dopant, the doped polymer has the ability to conduct electricity by the motion of either positively charged holes (a “p-type” conductor) or negatively charged electrons (an “n-type” conductor).
Currently, the p-type conductor PEDOT:PSS is the most common conducting polymer in use. PEDOT:PSS exhibits various convincing features like excellent ambient stability, high electrical conductivity, and most significantly, commercial availability as an aqueous dispersion.
But several electronic devices need a combination of n-types and p-types to function. Right now, there is no n-type comparable with PEDOT:PSS.
Scientists at Linköping University, together with their collaborators from the United States and South Korea, have designed a conductive n-type polymer ink that remains stable in air and even at higher temperatures. This new polymer formulation is called BBL:PEI.
According to Simone Fabiano, senior lecturer in the Department of Science and Technology at Linköping University, “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.”
Everything possible with PEDOT:PSS is also possible with our new polymer. The combination of PEDOT:PSS and BBL:PEI opens new possibilities for the development of stable and efficient electronic circuits.
Chi-Yuan Yang, Study Principal Author and Postdoc, Linköping University
Inexpensive and Easy
The latest n-type material is available in the form of ink along with ethanol as the solvent. The ink can be deposited by just spraying the solution onto a surface, which makes organic electronic devices simpler and inexpensive to manufacture.
Moreover, the ink is highly environmentally friendly compared to several other n-type organic conductors that are being developed at present, which contain detrimental solvents. Simone Fabiano is confident that the technology is all set for regular use.
Large-scale production is already feasible, and we are thrilled to have come so far in a relatively short time. 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.
Simone Fabiano, Senior Lecturer, Department of Science and Technology, Linköping University
The study was financially supported by the Knut and Alice Wallenberg Foundation, the Swedish Research Council, the Åforsk Foundation, the Olle Engkvist Foundation, Vinnova, and the strategic research area Advanced Functional Materials at Linköping University.
Yang, C.-Y., et al. (2021) A high-conductivity n-type polymeric ink for printed electronics. Nature Communications. doi.org/10.1038/s41467-021-22528-y.