Aseriesofcopolymers,basedonbenzo[1,2-b:4,5-b′]dithiophene（BDT）astheelectrondonorand2,1,3-benzothiadiazole（BT）/diketopyrrolo[3,4-c]pyrrole（DPP）astheelectronacceptors,weresynthesizedforhighlyefficientpolymersolarcells.BychangingtheBT/DPPratiointheconjugatedbackbone,theabsorption,energylevels,molecularaggregationandcarriermobilitycouldbefinelytuned.WithincreasedDPPcontent,theabsorptionrangewasextendedtothelongerwavelengthregionwithnarrowerbandgaps.Thehighestoccupiedmolecularorbital（HOMO）levelswerealsoraisedupandthemolecularaggregationwasenhanced.Thebalanceofthesefactorswouldaffordaremarkabledeviceperformanceenhancement.PolymerP3withBT:DPP=0.7:0.3（molarratio）exhibitedthehighestpowerconversionefficiency（PCE）of9.01%,withopencircuitvoltage(Voc)=0.73V,shortcurrentdensity(Jsc)=18.45mA·cm-2,andfillfactor（FF）=66.9%.ThePCEvaluewasimprovedby48.7%comparedtoP1andby117.6%comparedtoP7,respectively,indicatingagreatpotentialinphotovoltaicapplication.
