Light induced step-growth polymerization of Donor-Acceptor-Donor (DAD) type monomers based on thiophene - [1,2,5] Chalcogenazolo[3,4-f]-benzo [1,2,3] triazole - Thiophene

Two new donor-acceptor-donor(DAD) polymers type near-infrared (NIR) absorbing polymers containining thiophene as the donor and [1,2,5] chalcogenazolo [ 3,4-f]-benzo [1,2,3] triazole (chalcoen = S (P1a) or Se (P1b)) derivatives as the acceptor unit were designed and synthesized via light induced step-growth polymerization. The effect of different acceptor groups on the electrochemical and optical properties of the polymers was investigated. Highest occupied molecular orbital (HOMO) energy levels of the resultant black colored soluble polymers were calculated via cyclic voltammetry (CV) as -5.17 and -5.09 eV for P1a and P1b, respectively. Optical electronic band gaps were calculated as 0.81 and 0.74 eV for P1a and P1b, respectively. Lowest unoccupied molecular orbital (LUMO) energy levels were determined as -4.37 and -4.35 eV for P1a and P1b, respectively. NMR and gel-permeation chromatography (GPC) results supported the formation of high-molecular weight species. Synthesized polymers have promising features for application in various optoelectronic devices.