Handwritten and Sustainable Electronic Logic Circuits with Fully Printed Paper Transistors

Printed electronics answers to the emerging trend of using truly inexpensive and easily accessible techniques to design and fabricate low-cost and recyclable flexible electronic components. Nevertheless, printing of inorganic semiconductor materials arises some barriers for flexible electronics, as they usually may require high annealing temperatures to enhance their electronic performances, which are not compatible with paper. Here, the formulation of a water-based, screen-printable ink loaded with zinc oxide nanoparticles that does not require any sintering process is reported. The ink is used to create the channel in fully printed electrolyte-gated transistors on paper, gated by a cellulose-based ionic conductive sticker. The high conformability of the electrolyte-sticker mitigates the effect of the surface roughness of the channel, yielding transistors that operate under low voltage (<2.5 V) with a current modulation above 10⁴ and μ_Sat ≈ 22 cm² V⁻¹ s⁻¹. These devices operate even under moderate outward bending conditions. The screen-printed transistors are readily integrated in “universal” logic gates (NOR and NAND) by using ubiquitous calligraphy accessories for patterning of conductive paths and graphitic load resistances. This demonstrates the manufacturing of reliable and recyclable cellulose-based iontronic circuits with low power consumption, paving the way to a new era of sustainable “green” electronics.