All carbon nanotube based flexible field emission devices prepared through a film transfer method

Utilizing carbon nanotubes (CNTs) as substitutes for the conventional rigid indium-tin oxide (ITO) electrodes, all CNT based flexible field emission devices (FEDs) were possible to prepare with a novel film transfer method. In the method, both CNT-based flexible cathode and anode were fabricated by first attaching the vacuum filtered CNT film/mixed cellulose eater (MCE) filter membrane to an adhesive semi-cured poly(dimethyl siloxane) substrate, and then peeling off the MCE filter membrane. Effects of bending direction and bending radius on field emission properties were studied. The field emission performance of the convex bending device was worse than that of the flat device and deteriorated further with the decrease of bending radius. In contrast, the concave bending device exhibited better field emission properties than the flat device; nevertheless, its field emission properties decreased as the concave bending radius reduced below a certain value. The method achieved two successes. One is that the interfacial interaction between CNT films and the flexible substrate was greatly enhanced. The other is that the transfer process improved the field emission properties due to the increase of vertically aligned CNT tips. Compared with traditional methods applied in FED preparation, the novel modified transfer method is organic free, easy to control, cheap, and environment friendly.