Foldable and Recyclable Iontronic Cellulose Nanopaper for Low‐Power Paper Electronics

Abstract An increase in the demand for the next generation of “Internet‐of‐Things” (IoT) has motivated efforts to develop flexible and affordable smart electronic systems, in line with sustainable development and carbon neutrality. Cellulose holds the potential to fulfil such demands as a low‐cost green material due to its abundant and renewable nature and tunable properties. Here, a cellulose‐based ionic conductive substrate compatible with printing techniques that combines the mechanical robustness, thermal resistance and surface smoothness of cellulose nanofibrils nanopaper with the high capacitance of a regenerated cellulose hydrogel electrolyte, is reported. Fully screen‐printed electrolyte‐gated transistors and universal logic gates are demonstrated using the engineered ionic conductive nanopaper and zinc oxide nanoplates as the semiconductor layer. The devices exhibit low‐voltage operation (<3 V), and remarkable mechanical endurance under outward folding due to the combination of the robustness of the nanopaper and the compliance of the semiconductor layer provided by the ZnO nanoplates. The printed devices and the ion‐conductive nanopaper can be efficiently recycled to fabricate new devices, which is compatible with the circular economy concept.