Synthesis And Properties Of Alternating Copolymers Containing Thienopyridines Units

Conjugated polymers containing thienopyridines structural units have the advantages of narrow band gap,wide absorption range,strong ICT effect and good thermal stability.They are used in organic light-emitting diodes(OLED),organic solar cells(OPVs),organic field effect transistors(OFET),photodetectors,chemical/biological sensors and other fields have a wide range of applications.At present,conjugated polymers containing thienopyridines structural units are mainly synthesized by Suzuki coupling and Stille coupling.These methods need to pre-functionalize the monomers,prepare the corresponding halides and borate or organometallic compounds,and obtain conjugated polymers through polycondensation.The conjugated polymers prepared by these methods have high molecular weight and good structural regularity,but the synthesis route is long and the cost is high;some metal compounds have poor stability and are difficult to store;and toxic by-products(such as organotin derivatives)may be produced during the polycondensation reaction,causing environmental pollution.In response to these problems,this thesis uses direct arylation polymerization(DArP)to prepare donor-acceptor alternating copolymers containing thienopyridines structures,and systematically study the optical properties,electrical properties,and crystallinity of the copolymers.Thermal stability,investigated the OLED performance and photothermal performance of the copolymer.The main research contents are as follows:1.Three alternating copolymers(PTPBZ1-3)of thienopyridines and benzene-aromatics were prepared by DArP using 2,3-dimethylthienopyrazine and dibromides derivatives of fluorene,carbazole and silicofluorene as monomers.The chemical structure and molecular weight of the copolymer were characterized by NMR and GPC.The chemical structure and molecular weight of the copolymer were characterized by NMR and GPC.Using UV-Vis absorption spectrometer,fluorescence spectrometer,electrochemical workstation,X-ray diffractometer and thermogravimetric analyzer and other analytical methods,the optical properties,electrical properties,crystallinity and thermal stability of the copolymer were investigated respectively,and combined with DFT calculations discussed.UV-Vis absorption spectra of the three copolymers showed obvious intramolecular charge transfer(ICT)from donor unit to acceptor unit.The optical band gaps of PTPBZ1-3 were 1.87 eV,1.73 eV and 1.89 eV,respectively,which were close to the electrochemical band gaps.The thermal decomposition temperature(T_d,5%)of PTPBZ1-3 is higher than 390 °C,showing good thermal stability.The OLED devices with PTPBZ1-3 as the light-emitting layer showed saturated red light.The maximum brightness and current efficiency of the device were 1186 cd/m² and 0.63 cd/A,824 cd/m² and 0.29 cd/A,2543 cd/m² and 1.05 cd/A,respectively.The OPVs prepared with PTPBZ1-3 as the donor material and Y6 as the acceptor material all showed lower photoelectric conversion efficiencies,1.23%,0.86%,and 1.09%,respectively,which was basically close to the results of similar polymer photovoltaic devices reported in literature.2.Four alternate copolymers(PTPT1-4)of thienopyridines-thiophene were prepared by DArP using 2,3-dimethylthienopyrazine and thiophene dibromide derivatives.The chemical structure and molecular weight of the copolymer were characterized by NMR and GPC.The optical properties,electrical properties,crystallinity and thermal stability of the copolymers were investigated by UV-Vis absorption spectrometer,fluorescence spectrometer,electrochemical workstation,X-ray diffraction analyzer and thermogravimetric analyzer.And through the infrared thermal imaging system,the photothermal performance of PTPT1-4 was investigated.The results show that PTPT1-4 exhibits broad absorption at 600-900 nm,with the maximum absorption peaks at 695 nm,872 nm,755 nm,and 765 nm,respectively.The four copolymers have different degrees of absorption in the near-infrared region of the biological window.PTPT1-4 emits weak fluorescence,and the fluorescence quantum efficiencies in CHCl₃ solution is only 0.67%,0.21%,0.09%,and 0.12%,respectively.Therefore,it may have the potential as a photothermal reagent.Under 808 nm(0.7 W/cm²)laser irradiation for 10 minutes,the photothermal conversion efficiency of PTPT1,PTPT3 and PTPT4 tetrahydrofuran solutions were 8.4%,11.7%,and 19.0%,respectively.Under 880 nm(0.7 W/cm²)laser irradiation for 10 minutes,the photothermal conversion efficiency of PTPT2 tetrahydrofuran solution was 16.1%.