Synthesis and characterization of carbazole-benzothiadiazole-based conjugated polymers for organic photovoltaic cells with triazole in the main chain

We have synthesized a series of carbazole-benzothiadiazole-triazole based copolymers, poly[(N-9′-heptadecanyl-2,7-carbazole)-co-(5,5-(4′, 7′-di-2-thienyl-2′,1′,3′-benzothiadiazole)) -co-((4-(4-butylphenyl)-3,5-diphenyl-4H-1,2,4]triazole))] (PCz3TBTz) by Suzuki coupling polymerization. The optical and electrochemical properties of the copolymers could be tuned by changing the comonomer unit of triazole from 0% to 80%. Organic photovoltaic (OPV) cells were fabricated by blending the synthesized polymers as a donor and PCBM as an acceptor. The material solubility and film morphology were improved by introducing the triazole unit in the main chain. Improved OPV device performance of 1.74% was achieved in the presence of an optimal amount of triazole moieties.