The study of chemical structure is crucial in chemistry and materials science. Materials structures can be classified in various ways, and the most familiar approach is to classify them according to the dimension of the structure. For example, carbon composed of the same elements can be categorized into zero-dimensional (0D) fullerene, one-dimensional (1D) carbon nanotube, two-dimensional (2D) graphene, and three-dimensional (3D) diamond, but due to particular arrangements of atoms, the properties are significantly different depending on the structural dimension. Bearing this in mind, many organic structures were created by designing the symmetry of the molecules and using polymerization to control the size of the structure (bottom-up strategy). Depending on the structural dimension, the synthesized organic structures showed applicability to various applications such as gas separation, storage, membranes, catalysis, etc. However, covalently bonded organic structures are limited in some areas because they are thermally unstable and have low conductivity. Therefore, I have studied fused aromatic networks (FANs) structure as the energy materials to overcome the limitations mentioned above. The fused ring has no free torsional motion, allowing stable electron transfer and providing thermal and chemical stability.