Design,Synthesis And Application Of Organic Semiconductors Based On Perylene Diimides With Perfluoroalkyl Groups

Perylene diimides and their derivatives?PDIs?are excellent n-type organic semiconductors.Perfluoroalkyl groups are hydrophobic,oxygen repellent,thermal stable,and compounds with them can form ordered arrangements.Perfluoroalkylated PDIs are excellent air-stable organic semiconductors.However they are with poor solubility,which makes low-cost solution process impossible.In this study,a series of soluble perfluoroalkylated perylene diimides and conjugated polymers based on them were synthesized by introducing both alkyl and perfluoroalkyl groups to PDIs.The soluble perfluoroalkylated PDIs are synthesized as following: addition of olefins and perfluoroalkyl iodide,substitution with Na N₃,and catalytic hydrogenation afforded four aliphatic amine C_FC_H-NH₂ containing different alkyl and perfluoroalkyl groups,the overall yield was 70.5-87.3%.Four different alkyl and perfluoroalkyl substituted perylene imides?C_FC_H-PDIs?were synthesized by reaction of C_FC_H-NH₂ with perylene tetracarboxylic dianhydride?PDA?in the yield of 75.6-88%.It is shown that the size and ratio of alkyl and perfluoroalkyl groups have a significant effect on the solubility of C_FC_H-PDIs in organic solvents.4C_F8C_H-PDI shows maximum solubility in toluene and C_H2Cl₂> 400 mg / m L.All C_FC_H-PDIs have excellent thermal stability,and their 5% weight loss temperature is higher than 375 oC.4C_F8C_H-PDI and 4C_F6C_H-PDI show typical characteristics of liquid crystals,and they can self-assemble to ordered structures in the mesophase state.These four small molecules can be used as receptor materials in bulk heterojunction solar cells.Based on the fact that appropriate alkyl and perfluoroalkyl ratio can significantly increase the solubility of perylene imide,we synthesized a series of PDI-based conjugated polymers with perfluoroalkyl groups.The specific process is as following: Firstly,the dibromo-substituted perylene diimides?C_FC_H-PDIs-2Br?were synthesized by bromination of C_FC_H-PDIs,followed by the Stille coupling reaction of C_FC_H-PDIs-2Br with donor parts.These polymers have a strong visible absorption in the range of 300-800 nm,low LUMO energy levels and excellent thermal stability.