Synthesis And Characterization Of Perylene Diimide (PDI)-biphenyl Electron Acceptor Materials

Non-fullerene solar cells as one of the branches,compared with fullerenes,due to its good solubility,high stability and high energy level has become a hot research issue in this field,and its power conversion efficiencies also was increased from 1% to 15%.Perylenediimide has a hot topic with outstanding ad vantages such as strong visible light absorption,adjustable energy levels,and multiple chemical modification sites on the structure.The unsubstituted perylene diimide has a large conjugated planar structure,which is not conducive to solu tion processing and film formation,and the aggregation behavior of the molecu les can be controlled through the change of the molecular structure.This paper is based on a series of research work of brominated perylenedi-imides,which is discussed from the following three major aspects:The flexible alkyl chain is introduced into the amide position of the perylenediimide to increase the solubility,and the biphenyl group is introduced into the bay by a nucleophilic substitution reaction.Due to the steric hindrance eff ect of the benzene ring,the planar structure between the linking group and PD-I cannot be formed,which effectively weakens the π-π interaction between the molecules and reduces the degree of aggregation of the molecule.Bromotriphenylene are synthesized by a nucleophilic substitution reaction b-etween 1,4-diiodo-2-bromobenzene and phenylboronic acid.Terphenyl-phthalimi de-terphenyl was synthesized via nucleophilic substitution between terphenyl mo n-oboron and dibromoperylenediimide.Perylenediimide-terphenylhydrazones are s ynthesized by the same method.Compared to biphenyls,the steric hindrance ef f-ect of terphenyls increases the dihedral angle between the linker group and P D-I,which can more effectively reduce the aggregation ability between molecul-es.We substituted the benzene rings on both sides of terphenyl with thiophen e to obtain biphenylthiophene-phthalimide-biphenylthiophene.Compared with be nzene ring,the thiophene group has a smaller volume and a stronger negative electron capacity,which is favorable for absorption.