A low band gap conjugated polymer (P1) containing benzodifuran (BDF) units was synthesized via Stille coupling polymerization.The polymer exhibited good solubility in common organic solvents (chloroform

chlorobenzene

dichlorobenzene

etc)

excellent film forming properties and wide absorption range in visible region.Density function theory (DFT) studies showed P1 had planar molecular structure

which benefited the arrangement of molecular chain.The molecular weight of P1 was measured by gel permeation chromatography (GPC) and the thermal property was investigated with thermogravimetric analysis (TGA).A primary bulk heterojunction-typed polymer solar cell was fabricated with the blend of P1 and PC71BM as the photosensitive layer.The device based on structure of ITO/PEDOT:PSS/P1:PC71BM(1:1.5

weight ratio

with DIO as additive)/Ca/Al showed an open-circuit voltage (Voc) of 0.80 V

a short circuit current of 5.66 mA/cm2(Jsc)

a fill factor (FF) of 65.14%

and a power conversion efficienct (PCE) of 2.96% under the illumination of AM 1.5

100 mW/cm2.The result shows that the introduction of BDF groups can achieve a low bandgap polymer

and the polymer based on BDF groups has great potential in polymer solar cells.