Synthesis,photoelectric Properties And Self-Assembly Properties Of Regioregular Polythiophenes

Polythiophenes are considered to be promising materials because of their excellent photoelectric properties and thermal stability,chemical stability and biocompatibility.Thus,they have been widely applied in many fields such as organic photovoltaic（OPV）,light-emitting diode（OLED）,organic field-effect transistor（OFET）.In particular,the regioregular 3-position substituted polythiophene（rrP3ST）is connected by head-to-tail connection,so that the steric hindrance between repeat units is relatively small.The planar configuration not only facilitates the close packing of materials,but also increases the effective conjugation length,reduces the band gap energy,and improves the mobility of electrons.So,regioregular polythiophene havs superior photoelectric characteristics and uniqueness over its corresponding random polythiophene.In recent years,studies on the synthesis and properties of regioregular 3-position substituted polythiophene have attracted much attention.At present,organometallic catalytic method is the most important synthesis method for rrP3ST,including the McCullough method,Rieke method,GRIM method,Stille method,Suzuki method and other coupling polymerization methods.These polymerization methods often require the preparation of an organometallic compound in advance,and the active organometallic compounds are often required to be carried out in an extremely low temperature,anhydrous and oxygen-free environment.These methods not only have tedious action steps,but also require the polymer to be capped at the end of the reaction.Therefore,regioregular polythiophene derivatives synthesized by DHAP and C-H/C-H coupling have attracted a great deal of interest in recent years.The main research contents are as follows:1.Synthesis and characterization of a series of poly（3-ester thiophene）（P1-P6）.A series of poly（3-ester thiophene）（P1-P6）were synthesized by C-H/C-H coupling polymerization method.Using UV-Vis absorption spectrum,fluorescence spectrum,XRD diffraction,and electrochemical analysis methods,the effects of the volume of the 3-position alkyl ester on the polymerization reaction and product properties such as crystallinity,optical properties and electrochemical properties were studied in detail.The results show that the larger the volume of the 3-position alkyl ester is,the lower the crystallinity of the polymer product is,and the maximum UV-Vis absorption peak of the polymer in the solid state is significantly red-shifted compared to its solution state.Compared with poly（alkylthiophene）,the polymerization product has a lower ionization potential and can be used as a potential P-type material.2.Synthesis and characterization of poly（3-sulfonylthiophene）（PTSO）and poly（3-sulfanylthiophene）（PTS）.Highly regioregular PTS and PTSO were synthesized by direct arylation polycondensation.The crystallinity,thermal stability,optical and electrochemical properties of PTSO and PTS were compared using UV-Vis absorption spectroscopy,fluorescence spectroscopy,XRD diffraction,and electrochemical analysis.The results show that compared with PTS,the sterically hindered 3-position sulfonyl group of PTSO is not conducive to the formation of a regular structure of polythiophene main chain,and its crystallinity decreases,and the maximum absorption peak position of UV absorption spectrum shifts significantly.2.A comparative study on the self-assembly properties of regioregular PTS and PTSO.The nanostructures of PTSO and PTS were prepared by the mixed solvent method.The effects of experimental conditions,including the ratio of poor solvent,temperature and solvent polarity,on the self-assembly behavior of the two polymers were studied in detail.By adjusting the ratio of good solvent（CHCl₃）/poor solvent（CH₃OH）,PTSO forms nanospheres（200 nm）,while PTS forms nanoplatelets（200 nm-1μm）.Based on the experimental results,we proposed the self-assembly competition mechanism of the hydrophobic interaction andπ-πstacking interaction between chains.