Macromolecules, Vol.50, No.20, 8149-8157, 2017
Efficient All-Polymer Solar Cells Based on Conjugated Polymer Containing an Alkoxylated Imide-Functionalized Benzotriazole Unit
We developed a novel wide-bandgap conjugated polymer PTzBI-O based on an alkoxylated electron-deficient monomer (thiophen-2-yl) - [1,2,3] triazolo [4,5-f]isoindole-5,7 (2H, 6H)-dione (TzBI-O). Regarding that of alkyl-substituted imide-functionalized benzotriazole (TzBI) unit, the incorporation of oxygen atom into the substitution of TzBI-O increased the electronegativity. The resulting polymer PTzBI-O exhibited an absorption onset of 708 nm, corresponding to a bandgap of 1.75 eV. The PTzBI-O:N2200 blend exhibited strong aggregation in toluene solution, resulting in the enhanced absorptivity in thin film compared to those of equivalent films processed with chlorinated solvents, The fabricated all-polymer solar cell based on PTzBI-O:N2200 blend film processed with toluene exhibited an impressive power conversion efficiency of 7.91%. The higher efficiency of the toluene-processed device than those based on films processed With Chlorinated solvents can be attributed to more effective:charge dissociation, trivial bimolecular recombination, greater charge transportation, and more favorable-thin film morphology of the toluene-cast blend film. These findings indicated that the resulting copolymer has great potential for the construction of high-performance all-polymer solar cells.