Effect of Co-monomers on Triphenylamine-Thiazolothiazole-Based Donor-Acceptor Copolymers: Synthesis and their Optical Properties

Donor-Acceptor type copolymer, poly(9,9, di-n-hexylfluorenealt-2,5-bis(N,N-diphenylaniline)-thiazolo[5,4-d]thiazole) (P1) and random copolymers of P2-P4 have been synthesized using Suzuki polymerization reaction. For random copolymers, dicyanomethane derivative of triphenylamine, dithienothiophene and thienothiophene were used as co-monomers, respectively to P2-P4 along fluorene and 2,5-bis(N,N-diphenylaniline)-thiazolo[5,4-d]thiazole). Studies on the optical, thermal and electrochemical properties of these copolymers (P1-P4) were carried out. By incorporating different aromatic moiety as co-monomer, optical properties of the polymers were tuned which exhibited significant changes in UV Vis absorption as well as emission characteristics. All these copolymers were thermally stable upto 300 degrees C and soluble in common organic solvents. Electrochemical studies of these polymers indicate that they have deep HOMO energy levels. Photoluminescence emission studies of the synthesized polymers as thin film showed that polymer (P2) with dicyanomethane derivative of triphenylamine was red shifted when compared with other polymers. Weight average moleular weights of the polymers were in the range of 6.457 KDa to 12.000 KDa.