The molecular structure of a carbon nanotube CNT plays a crucial role in determining its electronic properties and charge transport behavior. Carbon nanotubes are cylindrical nanostructures composed of carbon atoms arranged in a hexagonal lattice, and they can be classified into two main types: single-walled carbon nanotubes SWCNTs and multi-walled carbon nanotubes MWCNTs . The electronic properties of CNTs are primarily influenced by their chirality, diameter, and the presence of defects.1. Chirality: Chirality refers to the arrangement of carbon atoms in the hexagonal lattice of the nanotube. It is defined by a pair of indices n, m , which determine the direction of the lattice vectors. Based on the values of n and m, CNTs can be classified into three categories: a. Armchair n = m : These CNTs exhibit metallic behavior, meaning they have excellent electrical conductivity and no bandgap. b. Zigzag m = 0 : These CNTs can be either metallic or semiconducting, depending on the value of n. If n is a multiple of 3, the CNT is metallic; otherwise, it is semiconducting. c. Chiral n m : These CNTs are generally semiconducting, with their bandgap depending on the difference between n and m.2. Diameter: The diameter of a CNT also influences its electronic properties. Smaller diameter CNTs typically have larger bandgaps, making them more semiconducting in nature. Conversely, larger diameter CNTs tend to have smaller bandgaps or even exhibit metallic behavior.3. Defects: The presence of defects in the carbon lattice, such as vacancies, impurities, or dislocations, can significantly impact the electronic properties of CNTs. Defects can introduce localized states within the bandgap, alter the band structure, and affect the charge transport behavior. In general, defects can reduce the electrical conductivity of CNTs and lead to more scattering of charge carriers.In summary, the molecular structure of a carbon nanotube, particularly its chirality, diameter, and the presence of defects, plays a critical role in determining its electronic properties and charge transport behavior. Understanding these relationships is essential for the development of CNT-based electronic devices and applications.