A new polyelectrolytic polyacetylene, poly(2-ethynyl-N-iodopyridinium triiodide), was applied for DSSCs. Poly(2-ethynyl-N-iodopyridinium triiodide) was prepared by the non-catalyst polymerization of 2-ethynylpyridine using iodine without any additional initiator or catalyst in high yields. The photoluminescence peak was observed at 534 nm corresponding to a photon energy of 2.32 eV. Quasi-solid-state DSSCs with a SnO2:F/TiO2/D719 dye/solid-state electrolyte/Pt device was fabricated with the poly(2-ethynyl-N-iodopyridinium triiodide) electrolyte, which shows the power conversion efficiency (PCE) of 5.79%.