Derivative based on 2, 7-dibromo-9-fluorenone-4-formic acid and synthesis method thereof

The invention discloses a derivative based on 2, 7-dibromo-9-fluorenone-4-formic acid and a synthesis method of the derivative, and belongs to the technical field of organic synthesis, the structure of the derivative is shown as formulas (I)-(III), an ester group is introduced to the 4 position of 2, 7-dibromo-9-fluorenone-4-formic acid through esterification reaction, on one hand, the solubility of a polymer based on the monomer can be improved, and on the other hand, the solubility of the polymer can be improved; on the other hand, the coplanar performance of the polymer is improved, charge transmission is facilitated, the mobility is improved, and the polymer is suitable for preparing transistors; malononitrile or alkyl-substituted rhodanine is introduced to a 9-position carbonyl active site, so that a polymer with a relatively narrow band gap can be obtained, the spectral absorption of the polymer can be improved, the open-circuit voltage and the photoelectric conversion efficiency of a polymer solar cell