First-Principles Calculations on the Emission Properties of Pristine and N-Doped Carbon Nanotubes

The electronic structures and field-emission properties for pristine and N-doped capped single-walled carbon nanotubes (CNTs) are investigated on the basis of density functional theory. The emission currents from three types of orbitals in CNTs are calculated under the applied electric field. Upon N-doping, total current increases about 4 times under a lower electric field, and 1.5 times under a higher electric field. Comparison between the emission currents from different orbitals shows that the orbital induced by N-doping plays an important role in the emission property of N-doped CNT. The effect of the doping position on the emission property for N-doped CNT is discussed, and the optimal N-doping configuration is obtained.