The morphology of active layer plays a critical role in determining the photovoltaic performance of organic solar cells(OSCs).However,binary blends often suffer from suboptimal phase separation,which limits the effici...The morphology of active layer plays a critical role in determining the photovoltaic performance of organic solar cells(OSCs).However,binary blends often suffer from suboptimal phase separation,which limits the efficiency of OSCs.Herein,two bridging polymer acceptors(PAs)—benzodithiophene-(2-ethylhexyl)oxy(BDT-C2C4)and benzodithiophene-octyloxy(BDT-C_(8))—are designed and synthesized by combining a benzodithiophene(BDT)unit as the donor moiety[poly({4,8-bis[5-(2-ethylhexyl)-4-fluorothiophen-2-yl]benzo[1,2-b:4,5-b']dithiophene-2,6-diyl}){5,8-bis[4-(2-butyloctyl)thiophen-2-yl]dithieno[3',2':3,4]},D18],and a 2,2′-((2Z,2′Z)-{[12,13-Bis(2-butyloctyl)-12,13-dihydro-3,9-dinonylthieno[2,3]thieno[3,2-b]pyrrolo[4,5-g]thieno[2,3-b]indole-2,10-diyl]bis(methanylylidene)}bis(3-oxo-2,3-dihydro-1H-indene-2,1-diylidene))dimalononitrile(Y6)derivative as the acceptor moiety.BDT-C2C4 and BDT-C_(8) are functionalized with(2-ethylhexyl)oxy and octyloxy side chains on the BDT unit,respectively.Both PAs show complementary absorption and cascaded energy levels with the donor D18 and the acceptor 2,2′-((2Z,2′Z)-{[12,13-bis(3-ethylheptyl)-3,9-diundecyl-12,13-dihydro-[1,2,5]thiadiazolo[3,4-e]thieno[2″,3″∶4′,5′]thieno[2′,3′∶4,5]pyrrolo[3,2-g]thieno[2′,3′∶4,5]thieno[3,2-b]indole-2,10-diyl]bis(meth⁃aneylylidene)}bis(5,6-difluoro-3-oxo-2,3-dihydro-1H-indene-2,1-diylidene))dimalononitrile(N3),but BDT-C_(8) exhibits better compatibility with D18 and N3 compared to BDT-C2C4.When incorporated as a third component into the D18∶N3 blend,both PAs improve the active layer morphology.In particular,the D18∶N3∶BDT-C_(8) blend shows significantly optimized morphology,featuring reduced phase separation and a fibrous network structure.As a result,the device based on D18∶N3∶BDT-C_(8) achieves a power conversion efficiency of 18.18%,significantly higher than that of the device based on D18∶N3(ca.17.37%).This work presents a compatibilizer strategy for optimizing blend morphology towards high-performance ternary OSCs.展开更多
文摘The morphology of active layer plays a critical role in determining the photovoltaic performance of organic solar cells(OSCs).However,binary blends often suffer from suboptimal phase separation,which limits the efficiency of OSCs.Herein,two bridging polymer acceptors(PAs)—benzodithiophene-(2-ethylhexyl)oxy(BDT-C2C4)and benzodithiophene-octyloxy(BDT-C_(8))—are designed and synthesized by combining a benzodithiophene(BDT)unit as the donor moiety[poly({4,8-bis[5-(2-ethylhexyl)-4-fluorothiophen-2-yl]benzo[1,2-b:4,5-b']dithiophene-2,6-diyl}){5,8-bis[4-(2-butyloctyl)thiophen-2-yl]dithieno[3',2':3,4]},D18],and a 2,2′-((2Z,2′Z)-{[12,13-Bis(2-butyloctyl)-12,13-dihydro-3,9-dinonylthieno[2,3]thieno[3,2-b]pyrrolo[4,5-g]thieno[2,3-b]indole-2,10-diyl]bis(methanylylidene)}bis(3-oxo-2,3-dihydro-1H-indene-2,1-diylidene))dimalononitrile(Y6)derivative as the acceptor moiety.BDT-C2C4 and BDT-C_(8) are functionalized with(2-ethylhexyl)oxy and octyloxy side chains on the BDT unit,respectively.Both PAs show complementary absorption and cascaded energy levels with the donor D18 and the acceptor 2,2′-((2Z,2′Z)-{[12,13-bis(3-ethylheptyl)-3,9-diundecyl-12,13-dihydro-[1,2,5]thiadiazolo[3,4-e]thieno[2″,3″∶4′,5′]thieno[2′,3′∶4,5]pyrrolo[3,2-g]thieno[2′,3′∶4,5]thieno[3,2-b]indole-2,10-diyl]bis(meth⁃aneylylidene)}bis(5,6-difluoro-3-oxo-2,3-dihydro-1H-indene-2,1-diylidene))dimalononitrile(N3),but BDT-C_(8) exhibits better compatibility with D18 and N3 compared to BDT-C2C4.When incorporated as a third component into the D18∶N3 blend,both PAs improve the active layer morphology.In particular,the D18∶N3∶BDT-C_(8) blend shows significantly optimized morphology,featuring reduced phase separation and a fibrous network structure.As a result,the device based on D18∶N3∶BDT-C_(8) achieves a power conversion efficiency of 18.18%,significantly higher than that of the device based on D18∶N3(ca.17.37%).This work presents a compatibilizer strategy for optimizing blend morphology towards high-performance ternary OSCs.
