Alternated Graphene/Carbon Nanotubes Sandwich Field Emitter for Making Ultra-Low-Voltage Field Emission Light Directly Driven by Household Electricity Supply

Field emission cathode electroluminescent lamp is a light source with multiple advantages including continuous light spectrum and high efficiency. However, it needs a high operation voltage of the order of kilovolts with transformer, because its emitters have limited cathode - anode distance at hundreds of microns and high operation electric field. This study makes graphene and carbon nanotubes (CNTs) hybrid field electron emitter with ultra-low turn-on field down to 0.1 V/
$\mu \text{m}$
. Their diode-structure field emission lamp can be directly driven by 110 V and 220 V household electricity supply and has bright luminescence with a very low power consumption of 14 mW. The emitters are made of alternated graphene/CNTs sandwich material, and their good field emission properties are attributed to these alternated graphene layers. During field emission, the graphene layers switch their function as spacers to reduce the screening effect at low operation field and also participate in electron emission at high operation field. This study offers a new strategy to make low power consumption and healthy light sources. Meanwhile, this study also raises the requirement to develop low voltage and high efficiency electronic luminescent phosphor.