Field emission enhancement by electric field activation in screen‐printed carbon Nanotube film

By applying a critical field treatment instead of the conventional surface treatments such as soft rubber roller, ion beam irradiation, adhesive taping, and laser irradiation, electron emission properties of screen‐printed carbon nanotubes (CNTs) were enhanced and investigated based on the emission current‐voltage characteristics through scanning electron microscopy. After nanotube emitters were activated at the applied electric‐field of 2.5 V/um, the electron emission current density with good uniform emission sites reached the value of 2.13 mA/cm2, which is 400 times higher than that of the untreated sample, and the turn‐on voltage decreased markedly from 700 to 460 V. In addition, enhancement of the alignment of CNTs to the vertical direction was observed.