Abstract: Photocatalysis has emerged as one of the most promising technologies converting the solar energy to chemical or electrical resources with the aims of visible-light utilization and devices' preparation. Basing on the factors restraining the photocatalytic efficiency because of the narrow photo-response range, low light absorption, and recombination of photo-generated holes and electrons, this paper focuses on the molecular aggregation owing large conjugation degree and the recent development of TiO₂ photocatalytic composites based on the organic materials (perylene and diketopyrrolopyrrole) possessing large conjugating degree and summarizes the methods applied in the improvement of photocatalytic efficiency and interface bonding. Finally, we look forward to the future research work concerning the development of photocatalytic materials.