Preparation Of Isoindigo-Based Conjugated Polymers By Aldol Condensation Reaction And Its Transistor Properties

In recent years, the conjugated polymer semiconductor materials in the application of organic thin film field-effect transistors ?OTFTs? have attracted more and more attention. It has the advantages of light weight, low cost, good flexibility and easy for solution processing or spin-coating. Due to the shortcomings of conventional polymerizations, including Stille and Suzuki, on the preparation of organic thin-film transistors, such as the monomer must be pre-functionalized, the toxicity of tin monomer is deep, the monomer is difficult to purify and the polymerization conditions are harsh. Two isoindigo-based D-A conjugated polymers were prepared by green efficient Aldol condensation reaction. The effects of solvents, catalysts, reaction time and other factors on the polymerization and the effects of these polymers in organic thin film transistors performance were studied. The main research work is as follows:1) A novel PIID-BT was synthesized by the reaction of Aldol with thiophene as the donor isoindigo as the acceptor. The solvents, reaction time, catalysts of Aldol condensation reaction in the preparation of the PIID-BT were studied systematically.The results showed that the reaction was successful and the average molecular weight of the polymer was 59.5 KDa. The optimum reaction conditions were as follows: 16 hours was the suitable reaction time, toluene was used as the solvent and toluene sulfonic acid as the catalyst. The results of 1H NMR, UV-Vis-NIR spectroscopy, electrochemical test data compare with that of Stille polymerization show that the molecular structure of the polymer is consistent with that of the target polymer. At the same time, the transistor performances of the polymer PIID-BT were tested. The hole mobility of the OTFTs was 0.163 cm²V^-1s^-1 at 290?.2) In order to make the Aldol condensation reaction more widely in the application of the isoindigo polymer, we designed and synthesized the isoindigo derivative PBIBDF-BT with BIBDF as the acceptor and bithiophene as the donor. Based on the achievements of the previous work, toluene as the solvent and toluene sulfonic acid as the catalyst, the effect of reaction time on the molecular weight of the polymer was investigated. When the reaction time was 72 hours, the number average molecular weight of the polymer reached 31.9 KDa. The results of 1H NMR, UV-Vis-NIR spectroscopy, electrochemical test data compare with that of Stille polymerization show that the molecular structure of the polymer is consistent with that of the target polymer.At the same time, the performances of the polymer PBIBDF-BT were tested. The devices exhibited hole-transporting performances in air, and the hole mobility was 0.258 cm²V^-1s^-1 at 310?. The electron transport performances were exhibited in vacuum, and the highest mobility was 0.257 cm²V^-1s^-1 at 310 ?.