Nanocellulose foils for three-dimensional electronics

Tengu joshi, a special kind of japanese handmade paper, is known as the world’s thinnest paper. These papers have an ultralow basis weight (≥2 g/m²), are translucent, and are porous with a fabric-like structure. In contrast to that, we report here the fabrication of sprayed paper foils on the same size scale. We use a new protocol which includes the spraying of aqueous TEMPO-nanocellulose (TCNF) fibrils ink layer-by-layer on a hot substrate using a movable spray nozzle. The resulting foils are 2±1 µm thin with an average basic weight of only 1.9 g/m², which is ranging on the same scale as the world’s thinnest paper. The foils are highly transparent, non-porous, and have good mechanical properties. In addition to that, we combine our foils with silver nanowires (AgNWs) and poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS), which makes them conductive. We demonstrate the applicability of our TCNF foils by forming curved, self-supporting 3D shapes out of them. With this, we went another step towards sustainable, lightweight, three-dimensional organic electronics.