Strain effects on work functions of pristine and potassium-decorated carbon nanotubes

TL;DR

This study investigates how uniaxial strain and potassium doping influence the work functions of specific carbon nanotubes, revealing strain-dependent behaviors and potential for electronic device optimization.

Contribution

It provides a detailed first-principles analysis of strain and doping effects on CNT work functions, highlighting new ways to control electronic properties.

Findings

Work functions of CNTs are strongly affected by uniaxial strain.

Potassium doping significantly lowers work functions by over 2 eV.

Strain dependence of work functions changes notably with chemical coating.

Abstract

Strain dependence of electronic structures and work functions of both pristine and potassium doped (5,5) (armchair) and (9,0) (zigzag) carbon nanotubes (CNTs) has been thoroughly studied using first-principles calculations based on density functional theory (DFT). We found that for pristine cases, the uniaxial strain has strong effects on work functions of CNTs, and the responses of work functions of CNT (5,5) and (9,0) to the strain are distinctly different. When the strain changes from -10% to +10%, the work function of the CNT (5,5) increases monotonically from 3.95 eV to 4.57 eV, and the work function of the (9,0) varies between 4.27 eV and 5.24 eV in a complicated manner. When coated with potassium, for both CNTs, work functions can be lowered down by more than 2.0 eV, and the strain dependence of work functions changes drastically. Our studies suggested that the combination of chemical coating and tuning of strain may be a powerful tool for controlling work functions of CNTs, which in turn will be useful in future design of CNT-based electronic and field-emitting devices.