Graphene oxide discovery points to flexible nanoelectronics

Because of disruptions within its bonding structure, graphene oxide is not as conductive as graphene itself. However, researchers from the World Premier International Centre for Materials Nanoarchitectonics (WPI-MANA) found that by adjusting the percentages of the energy levels within its structure, they were able to fine tune band gaps and therefore control conductivity. Current methods for controlling bandgaps in graphene oxide are usually chemically based, expensive, and cannot be used within electronic components themselves. The technique devised by the WPI-MANA scientists enables non-volatile tuning of bandgaps in multi-layered graphene oxide within an all-solid-state electric double layer transistor (EDLT). The EDLT comprises graphene oxide on a silica glass substrate gated by a zirconia proton conductor. The team triggered a reversible electrochemical reduction and oxidation (redox) reaction at the graphene oxide/zirconia interface by applying a dc voltage. This in turn caused proton migration from the graphene oxide through the zirconia. The redox reaction created reduced graphene oxide, or rGO, and caused a fivefold increase in current in the transistor. Tests have shown that the rGO retained conductivity for more than one month without further voltage application. What's more, compared with field-effect transistors, the new EDLT uses far less voltage to switch between on and off phases, meaning it is cheaper to use. "This new method for fine tuning conductivity could lead to control over optical and magnetic properties of components, with far reaching applications," said lead researcher Kazuya Terabe.