Wepresenthereaseriesofperylenediimide(PDI)basedisomericconjugatedpolymersfortheapplicationasefficientelectronacceptorsinall-polymersolarcells(all-PSCs).BycopolymerizingPDImonomerswith1,4-diethynylbenzene(para-linkage)and1,3-diethynylbenzene(meta-linkage),isomericPDIbasedconjugatedpolymerswithparallelandnon-parallelPDIunitsinsidebackboneswereobtained.Itwasfoundthatpara-linkedconjugatedpolymer(PA)showedbettersolubility,strongerπ-πstacking,morefavorableblendmorphology,andbetterphotovoltaicperformancethanthoseofmeta-linkedconjugatedpolymers(PM)did.DevicebasedonPTB7-Th:PA(PTB7-Th:poly{4,8-bis[5-(2-ethylhexyl)-thiophen-2-yl]benzo[1,2-b:4,5-b’]dithiophene-2,6-diyl-alt-3-fluoro-2-[(2-ethylhexyl)-carbonyl]thieno[3,4-b]thiophene-4,6-diyl})showedsignificantlyenhancedphotovoltaicperformancethanthatofPTB7-Th:MA(3.29%versus0.92%).Moreover,thephotovoltaicperformanceofthesepolymericacceptorscouldbefurtherimprovedviaaterpolymericstrategy.Bycopolymerizingasmallamountofmeta-linkagesintoPA,theoptimizedterpolymericacceptorsenabledtoenhancephotovoltaicperformancewithimprovedtheshort-circuitcurrentdensity(Jsc)andfillfactor(FF),resultinginanimprovedpowerconversionefficiency(PCE)of4.03%.
