Fused imidazole monomers (1b, 1li, and 2b) having the octyl group were synthesized by the microwave-assisted intramolecular direct arylation, which were subjected to the cross coupling polymerization. For obtaining g-conjugated polymers with better solubility, fused imidazole monomers (si-1b and si-3b) having the bulky trisiloxane-terminated decyl chain were likewise synthesized and polymerized. On the basis of absorption and emission spectra of obtained pi-conjugated polymers in conjunction with the X-ray crystal structure theoretical calculation, the fused structure and coupling partner were found to affect the optical properties in CHCl3 solution as a result of steric and electronic factors. The spectroscopic measurements in film revealed that the bulky trisiloxane group helps conjugated, polymers to form the rc-stacked structure upon thermal annealing. The proton doping experiment was also carried out to find out that the protonation of imidazole nitrogen results in the different peak shift depending on the comonomer structure.