Electron field emission from screen-printed graphene/DWCNT composite films

The electron field emission properties of graphene/double-walled carbon nanotube (DWCNT) composite films prepared by screen printing have been systematically studied. Comparing with the pure DWCNT films and pure graphene films, a significant enhancement of electron emission performance of the composite films are observed, such as lower turn-on field, higher emission current density, higher field enhancement factor, and long-term stability. The optimized composite films with 20% weight ratio of graphene show the best electron emission performance with a low turn-on field of 0.62 V μm−1 (at 1 μA cm−2) and a high field enhancement factor β of 13,000. A model of the graphene/DWCNT composite films is proposed, which indicate that a certain amount of graphene will contribute the electron transmission in the silver substrate/composite films interface and in the interior of composite films, and finally improve the electron emission performance of the graphene/DWCNT composite films.

► The field emission performance improved significantly when adding graphene into DWCNTs as the emission material.
► We set up a model of pure DWCNT films and graphene/DWCNT composite films.
► We discussed the contact barrier between emission films and electric substrates by considering the Fermi energies of silver, DWCNT and graphene.