Fully Printed and Flexible Schottky Diodes Based on Carbon Nanomaterials Operating Up to 5 MHz

The capability to fabricate printed and flexible energy harvesting and conditioning circuits, over a large area and with low-cost techniques, is crucial to enable flexible and wearable electronics. Carbon nanomaterials show excellent electrical, optical, chemical, and mechanical properties for printed electronics, offering low-cost, and large-area functionality on flexible substrates. In the past few years, many efforts have been dedicated to the fabrication of printed transistors made with carbon nanomaterials, but very few works have been dedicated to diodes, which are fundamental circuit elements, often employed in energy harvesting systems. Here we report a simple and cost-effective approach for the fabrication of fully inkjet-printed Schottky diodes on Kapton and paper substrates using carbon nanotubes (CNT) and graphene. We demonstrate that both ohmic and Schottky contacts between printed nanotubes and graphene can be obtained with post-printing thermal treatments at different temperatures. The diodes thus fabricated work with low supply voltages, exhibit excellent mechanical stability and have a maximum operating frequency in the order of 5 MHz.