To obtain a better understanding of the photophysical and electronic properties, density functional theory (DFT) calculations for small molecules and polymers were performed at the B3LYP/6-31G(d) level of theory using the polarizable continuum model (PCM) solvation model (solvent: CH3CN). The polymers were modeled as short chains containing three structural units (CP1-T and CP2-T) to keep the calculations manageable. The frontier orbitals diagrams, optimized structures and the coordinates are included in the SI (Figures S10-S14, Table -S6). For small molecules 1 and 2, the highest occupied molecular orbitals (HOMOs) are localized over the biphenyl or bithiophene linker. The calculated energy gap between HOMO and LUMO for 1 is larger than 2, consistent with the experimental trend. The contour plots of the five lowest unoccupied orbitals (LUMO to LUMO+4) reveal that LUMOs are largely distributed on the carbonylpyridinium units. Representative frontier orbitals HOMO, and LUMO to LUMO+4 as well as the calculated orbital energy levels are shown in Figure . The energy gaps between LUMO and LUMO+1, LUMO+3 and LUMO+4 are very small (less than 0.35 eV, indicative of their degenerative nature). Interestingly, the LUMO+2 orbitals display a large contribution from the central linker, indicating that the extended linker may also play a role in accepting electrons. It is well-known that the LUMO energy level of n-type electroactive materials is a useful parameter for estimating its relative redox potential (a lower LUMO energy level corresponds to a higher reduction potential). Assuming that the electron configurations are rigid, electrons will successively fill the unoccupied orbitals from the lowest to the highest-energy orbital during the reduction process.