Outstanding field emission performance via superior carbon nanotubes dispersion by acoustic resonance mixing and synergistic function-oriented annealing strategy

Abstract

The homogeneous dispersion of carbon nanotubes (CNTs) is a key bottleneck limiting breakthroughs in cold cathode field emission performance. Due to strong intermolecular van der Waals forces between CNTs, agglomeration readily occurs, resulting in field emission shielding effects that severely impair emission performance. Traditional ball milling methods suffer from drawbacks such as long time consuming, low efficiency, and structural damage to CNTs during dispersion. This study proposes a composite collaborative strategy combining acoustic resonance mixing with function-oriented annealing. Acoustic resonance mixing achieves highly efficient and homogeneous dispersion of carboxylic multi-walled carbon nanotubes (COOH-CNTs) while effectively preserving the structural integrity of the CNTs. Simultaneously, employing the function-oriented strategy to control the annealing temperature, the surface carboxyl functional groups of COOH-CNTs were effectively removed, thereby significantly enhancing their field emission performance. Furthermore, we conducted FLUENT numerical simulations to validate the superiority of the acoustic resonance mixing technology in dispersing CNTs. Experimental results demonstrate that the CNTs emitters fabricated using this synergistic strategy exhibit exceptionally low turn-on and threshold electric fields of 1 V/μm and 1.26 V/μm, respectively. The emitters achieve a field emission current density of 24.4 mA/cm² at an electric field of 2.36 V/μm, a high field enhancement factor (β) of 9203, and minimal current fluctuation of only 3.4%, showcasing outstanding field emission stability and comprehensive performance. This study provides a novel technical approach for fabricating and optimizing the performance of high-performance cold cathode emitters.