A series of new conjugated polymers with evolving frontier orbitals (HOMOs and LUMOs) have been designed, synthesized, and characterized for potential polymer based photon harvesting device applications such as solar cells and photo detectors. The relationships between monomer or repeat unit side groups, frontier orbitals of the polymer, and changes in optoelectronic and physical properties of the polymer systems have been systematically investigated and correlated. For instance, when comparing the properties of the newly synthesized polymers in two groups: sulfone-based and phenyl-based, the difference in thermal stability and optical properties were consistent when changing from the carbazole monomer unit to the terephthaldicarboxaldehyde. The polymers containing the carbazole unit exhibited increased thermal stability, blue shift of optical absorption, higher frontier orbitals, and larger band gaps than the terephthaldicarboxaldehyde containing counterparts. These could be attributed to the higher electron density of the carbazole than the terephthaldicarboxaldehyde, and the possible deviation from planarity in the polymer main chain due to possible steric hindrance of the branched substituents.