A newly planar dithiafulvene sensitizer (DTF-C4) trending to form J-aggregates on the surface of mesoporous TiO2 by simply rinsing with a poor solvent acetonitrile was synthesized. We further show that the self-assembled J-aggregates optimized the TiO2surface utilization, enhanced the light harvesting ability by broadening and red-shifting the absorption, and suppressed the electron recombination, thereby significantly promoting the solar cell efficiency. Compared to the photoanode surface modified with DTF-C4 and the classical coadsorbent chenodeoxycholic acid (CDCA), the DSC based the DTF-C4compact J-aggregates exhibited a dramatically improved performance without the loss of adsorbed dyes, uplifting the power conversion efficiency from 4.68% to 7.48% alongside with a high open-circuit voltage of above 850 mV, which is higher than that of the commercial N719-based cell (770 mv).