Two fluorene- and carbazole fused triphenylamine-based metal-free organic polymer sensitizers that use 2-nitropyridine as a new acceptor anchoring mode but with different π-bridges of fluorene (FT04) and carbazole (CT04) have been designed, synthesized, and used as photosensitizers for dye-sensitized solar cells (DSSCs). Introduction of an imine unit into the π-bridge and extension of the π-bridge can dramatically improve the light-harvesting ability of DSSCs and suppress the electron recombination, thus uplifting their performance. The solar cell based on FT04 exhibited a broad incident photon-to-current conversion efficiency spectrum and high conversion efficiency (η=4.95%). However, under the same measuring conditions, the polymer sensitizer CT04, which has a similar structure as that of FT04 but without the imine unit in the conjugated π-bridge, gave an η value of 3.50%, indicating that the sensitizers are promising candidates to improve the performance of DSSCs. The better cell performance of FT04 than that of CT04 can be attributed to better light harvesting and better dark current suppression.