Synthesis and characterization of conjugated polymers containing bromide side chain

A series of copolymers PC8DTBT-x (x denotes the content of brominated units) were achieved by varying the amount of the brominated carbazole. The chemical structures, electrochemical properties, optical properties and photovoltaic performance of these copolymers were well characterized. The bromide side chains don't influent the frontier orbital levels of the conjugated polymers. The absorption coefficiency and fluorescence spectra of copolymers can be changed by the content of bromide units. Higher open circuit voltage and higher fill factor were observed in the organic solar cells using bromide-unit containing copolymers as the donor materials. When the content of bromide units reached 30%, higher absorption coefficiency and higher power conversion efficiency were achieved.