Flexible 3D Graphene Transistors with Ionogel Dielectric for Low-Voltage Operation and High Current Carrying Capacity

In this paper, an ionogel-gated flexible 3D graphene transistor made from graphene foam, consisting of a network of few layers graphene, is reported. The presented transistor, fabricated on thin, 28 mu m parylene, flexible substrate, demonstrates low-voltage operation (<= 2.5 V) and exhibits 4.78 times higher current capacity than previously reported liquid-gated 3D graphene transistor fabricated on glass substrate. This is also 26.72 times higher current capacity (93 mA at 2 V applied V-D) than the equivalent long channel (approximate to 600 mu m) 2D transistor device. The high current capacity and low operating voltage of this transistor are attributed to higher surface area, 3D structure of the transistor, and the high capacitive coupling between the ionogel gate and graphene. The transistor is thoroughly characterized for I-V characteristics and evaluated for circuit functionality. As a representative example, high current capacity was demonstrated by driving an LED where brightness depends on the current level through them which was tuned using the gate bias of the 3D transistor. The proposed transistor may find application in large-area electronics for interactive displays and for large-area sensors in structural health monitoring.