Field emission property of printed CNTs-mixed ZnO nanoneedles

ZnO nanoneedles were synthesized via thermal evaporation method without any catalyst. Scanning electron microscopy and transmission electron microscopy investigations showed that these products presented a nanoneedle structure. To enhance the field emission (FE) properties of screen printed ZnO nanoneedles, a given amount (0.05 g) carbon nanotubes (CNTs) mixed with (0.5 g) ZnO nanoneedles paste via screen printed method and heat-treatment at (600 °C, 500 °C and 450 °C) was presented. The CNTs-mixed ZnO nanoneedles heat-treated at 450 °C had the lowest turn-on field of 3.75 V/μm, highest field emission current of 0.16 mA at 7.5 V/μm and highest β of 830. An efficiency FE enhancement of 450 °C sample was attributed to melioration of conductance between ZnO nanoneedles and ITO surface by CNTs.