The principle of conductive film mainly depends on the movement of free electrons and holes inside it, as well as the crystal structure and defects of the material. Different types of conductive films have different conductive mechanisms due to their different material properties.
Conductive mechanism of different types of conductive films
Metallic conductive film: such as gold, silver, copper and other metals, its conductive mechanism mainly depends on the free electron theory. The outer electrons of metal atoms can move freely in the lattice. When the external electric field acts on the metal conductive film, the free electrons move in a directional manner under the action of the external electric field force to form a current. This mobility of free electrons makes the metal highly conductive.
Metal oxide conductive film: such as ITO (indium tin oxide), FTO (fluorine-doped tin oxide), AZO (aluminum-doped zinc oxide). The conductive mechanism of these materials mainly depends on intrinsic defects and impurity defects. For example, the vacancy of oxygen atoms in the ITO lattice leads to unequal oxygen ions, resulting in excess free electrons, thus having conductivity. In addition, doped high-valent cations can increase the concentration of free electrons and further improve conductivity.
Carbon-based conductive film: such as carbon nanotubes, graphene and other materials. These materials are composed of polymer chains, and the conjugated double bonds on the molecular chains can support the free transmission of electrons and form conductive channels. Although its conductivity is low, it has the characteristics of plasticity and low cost, and the conductivity can be adjusted by doping and other methods.