Study Of Electrochromic Materials Taking Thiophene And Fluorene As Electron Donors

Conducting polymers could be applied to display materials,light-emitting diode(LED),electrochemical cells and other fields due to their special conductivity and electrochromic property.There are many advantages for organic conducting copolymers,such as high optical contrast,easy processability,fast response time and so on.In the paper,nine donor-acceptor(D-A)type copolymers were synthesized successfully by chemical copolymerization,afterwards,a series of characterizations were carried out,including cyclic voltammetry(CV),UV-Vis-NIR spectroscopy,density functional theory(DFT),colorimetry,thermal gravimetric analysis,and so on.According to the dates we got,we can know the effect different units have on the resulting copolymer.Nine donor-acceptor conducting copolymers were synthesized through Stille coupling reaction and Suzuki coupling reaction.At first,two novel electrochromic polymers,poly(benzodithiophene-benzotriazole)(PBDBT)and poly(s-indacenodithiophene-benzotriazole)(PIDBT)were synthesized successfully.Based on the two copolymers,another acceptor unit,benzothiadiazole,was introduced to the copolymers,and poly(benzotriazole-indacenodithiophene-benzothiadiazole)(PBTIDBD)and poly(benzotriazole-benzodithiophene-benzothiadiazole)(PBTBDBD)were synthesized successfully.Then,the effect of acceptor unit was also investigated through fixing the donor unit,fluerene,four copolymers,poly(fluorene-pyrido[3,4-b]pyrazine)(PFPP),poly(benzotriazole-fluorene-pyrido[3,4-b]pyrazine)(PBTFPP),poly(benzotriazole-fluorene-benzothiadiazole)(PBTFBD)and poly(benzothiadiazole-fluorene-benzothiadiazole)(PBDFBD)were synthesized successfully.At last,benzoselenadiazole was investigeted through copolymerization with benzo[1,2-b:4,5-b’]dithiophene,poly(benzo[1,2-b:4,5-b’]di-thiophene-benzoselenadiazole)(PBDTBS)was synthesized successfully.The results show that,the copolymers taking benzodithiophene,indacenodithiophene as donor units,benzotriazole,benzothiadiazole as acceptor units show great properties,manifesting high optical contrast,fast response time and high coloration efficiency.The electrochromic property and stability of PFPP is not very good,and except for PFPP,all the other eight copolymers could be applied to electrochromic areas.