Enhancing Field Emission in Air via Ultrascaled Nanorod Electrodes

Enhancing field emission in ultrascaled electronics improves the device performance and energy efficiency. Conventional lithography defines electrodes with a few-nanometer spacing on the cost of strengthened electron scattering and the reduced field enhancement factor, thus presenting challenges to enhance field emission at a small bias. Here, we used self-assembled nanorods with sub-5 nm spacing as electrodes to overcome these challenges. Intrinsic ballistic transport through high-crystallinity solution-synthesized nanorods minimized charge scattering; meanwhile ultrascaled anisotropic morphologies concentrated local electric fields and thereby lowered the barrier height. Enabled by these structural features, we demonstrated field emission density up to 4.1 × 10⁴ A cm^-2 at 1 V in air, more than 10-fold higher than typical molecular and vacuum electronics at similar conditions, and constructed an air-operating electron source with an on/off ratio of 10⁵ at the collector electrode. Energy-efficient high-conductance electron emission suggested the potential of using solution-synthesized nanomaterials in ultrascaled electronics.