Nanoarchitected films for unbreakable flexible electronics

Priv. Doz. Dr. Megan Cordill, Erich-Schmid-Institut für Materialwissenschaft Prof. Damien Faurie, Laboratoire des Sciences des Procédés et des Matériaux LSPM - CNRS UPR3407 Foldable and rollable electronic displays as well as wearable sensors are almost a reality for consumers. The main technological obstacle is manufacturing these innovative devices to be unbreakable. Devices, such as the Samsung foldable phone, need to be mechanically and electrically durable for 100,000 folding or stretching cycles. Up until now, the micro- and nanosized flexible electronics cannot withstand the mechanical loading (folding or stretching) because cracks form which stop the electric current flow, causing the device to no longer function. A possible solution is to properly tailor the thin materials used in flexible devices in order to generate electrically conductive materials that do not break. The research team made of Austrian and French partners will create unique thin film materials (less than 1 m thick) by patterning two or more metals to form 1D, 2D and 3D nanomaterials, or nanocomposites. Through the combination of high strength and conductive metals with micro- and nanoscale patterning made with a special 3D printer, unbreakable nanomaterials ideal for foldable and stretchable electronics will be discovered. Not only will the team create these new materials, they will also test the various nanostructured systems by stretching (along one and two axes) and folding. The testing methods that will be used are only available within both partner s laboratories and the experimental techniques can directly connect the mechanical behavior with the electrical behavior by 3D imaging the surfaces, measuring the electrical resistance, or even measuring the stresses that evolve during stretching or folding. The results from this project will remove the technological obstacle and finally make foldable, rollable, stretchable, and wearable electronic devices available to customers. 1

Foldable and rollable electronic displays as well as wearable sensors are becoming a reality for consumers. The main technological obstacle is manufacturing these innovative devices to be unbreakable. Devices, such as the Samsung foldable phone, need to be mechanically and electrically durable for 100,000 folding or stretching cycles. Up until now, the micro- and nanosized flexible electronics cannot withstand the mechanical loading (folding or stretching) because cracks form which stop the electric current flow, causing the device to no longer function. The NanoFilm project addressed these challenges by studying how the different thin metal layers used can be tailored with optimum thickness, order of layers, and internal stresses to create fracture resistant layers. The electrical and mechanical behavior were examined using novel testing the allows measuring the electrical resistance and the internal stresses in the layers that cause fracture while stretching along one and two axes and bending. The research team made of Austrian and French partners investigated bi- and tri-layer films (less than 1 m thick) as well as complex alloys that can heal cracks that form. The self-healing capabilities will increase the lifetime of flexible devices and sensors. The results from this project will remove the technological obstacle and finally make foldable, rollable, stretchable, and wearable electronic devices available to customers.