Scientists develop solution for transparent electronic devices

Scientists at the Max Planck Institute for Polymer Research (MPI-P), led by Dr. Kamal Asadi, have resolved a four decades a long-term challenge in producing very thin nylon films that can be used, for example, in electronic memory components. Nylon thin films are 100 times thinner than hair and could therefore be of interest for applications in bendable electronic devices or clothes in clothing.

While the microelectronics industry is now moving towards portable electronic gadgets and electronic textiles, electronic materials such as ferroelectrics should be integrated into our clothing. Nylons, a family of synthetic polymers, were introduced for the first time in the 1920s for women's stockings and are now among the most widely used synthetic fibers in textiles. They consist of a long chain of repeated molecular units, that is to say.polymers, where each repeating unit contains a specific arrangement of hydrogen, oxygen and nitrogen with carbon atoms.

In addition to the use in textiles, it has been discovered that some nylons also have so-called "ferroelectric" properties. This means that the positive and negative electrical charges can be separated and that state can be maintained. Ferroelectric materials are used in sensors, actuators, memories and energy recovery devices. The advantage of using polymers is that they can be liquefied with appropriate solvents and thus converted into a low-cost solution in order to form flexible thin films suitable for electronic devices such as capacitors, transistors and diodes. This makes ferroelectric polymers a viable choice for integration with electronic textiles. Although nylon polymers have over the years found important commercial applications in fabrics and fibers, their application in electronic devices has been hampered by the fact that it was impossible to create thin films of ferroelectric nylons of high quality by solution treatment.

MPI-P scientists, in collaboration with researchers from the Johannes Gutenberg University of Mainz, and the Lodz University of Technology have solved this forty-year-old problem and developed a method of manufacturing of ferroelectric nylon thin film capacitors by dissolving nylon in a trifluoroacetic mixture acid and acetone and solidify it again under vacuum. They were able to make thin nylon films with a thickness of typically 100 nanometers, which is several times thinner than hair. "Using this method, we produced extremely smooth thin films. This is very important because it avoids electrical failures of capacitors, for example, and the destruction of electronic circuits. At the same time, the fineness makes it possible to have transparent thin layers and possibly transparent electronic devices. "Says Dr. Kamal Asadi, group leader at MPI-P.

Using their newly developed method, the group around Kamal Asadi has been able to produce high performance nylon capacitors. Scientists have subjected prototypes of capacitors to prolonged stress cycles and have demonstrated the robustness of ferroelectric nylons in millions of operating cycles. Thin nylon films could become an important component for use in flexible electronics in the future and find applications in electronic devices that can be bent or for electronics in clothing. These new discoveries pave the way for multifunctional tissues that serve as a fabric to cover our body and can at the same time generate electricity from the movements of our body.

Their results have now been published in the famous journal "Science Advances".