Design And Synthesis Of High Fluorescent Electrochromic Conjugated Polymers

Recently,research on electrochromic polymers has been under increased development.Current interest in this field has focused on some aspects such as full-color,solution-processable,high contrast materials with excellent performances,as well as features like potential bifunctional materials such as electrofluorochromisms.In this thesis,we designed and synthesized a series of electrochromic conjugated polymers based on 3,6-alkyoxy-thieno[3,2-b]thiophene building block,and discussed the strategies of tuning the neutral and oxidized absorption properties,as well as their fluorescence behaviors.Firstly,we utilized both backbone and side chain engineer to obtain a neutral red electrochromic polymer.A series copolymers containing fixed 3,6-bis(dodecyloxy)thieno[3,2-b]thiophene(DOTT)and different aromatic building blocks(bithiophene,benzene and dimethoxybenzene)were prepared through Pd-catalyzed chemical copolymerization,among which the soluble polymer PDOTT-MePh demonstrated a rapid switching between red and pale blue under applied voltages between 0 and 1.3 V,with moderate contrast and excellent stability.This indicated that the target of tuning the neutral optical properties of polymers has been achieved.The result revealed that substituting the moieties for copolymerization can modify the optical spectra of polymers and thus control the neutral color effectively.Next,we tried to substitute H atom on thiophenes in the backbone of polymer PDOTT-AcDOT with branched alkyoxy side chains and made a comparison with the unsubstituted polymer(PDOTT-T).The strategy was found to be effective in enhancing the transmittance of oxidized polymer films and optimizing the contrast.Additionally,to develop electrofluorochromic polymers as candidates for emissive-reflective bifunctional displays,we discussed the fluorescent properties of all polymers mentioned above.The results demonstrated that PDOTT-MePh,PDOTT-AcDOT and PDOTT-T showed stronger fluorescence in solution,while PDOTT-MePh could emit red light at a higher intensity in solid film state.Furthermore,to our surprise,the emission of PDOTT-MePh device could be quenched by electrochemical doping and recover to a certain degree during the dedoping process,which makes polymer PDOTT-MePh a promising candidate of electrofluorochromic bifunctional materials.These works not only brought us a series of interesting optoelectronic materials,but also become an inspiration for us to develop multifunctional materials and applications further.