Polymer solar cells with an inverted device configuration using polyhedral oligomeric silsesquioxane-[60]fullerene dyad as a novel electron acceptor

A polyhedral oligomeric silsesquioxane-[60]fullerene (POSS-C60) dyad was designed and used as a novel electron acceptor for bulk heterojunction (BHJ) polymer solar cells (PSCs) with an inverted device configuration. The studies of time-resolved photoinduced absorption of the pristine thin film of poly[(4,4'-bis(2-ethylhexyl)dithieno[3,2-b:2',3'-d]silole)-2,6-diyl-alt-(4,7-bis (2-thienyl)-2,1,3-benzothiadiazole)-5,5'-diyl] (SiPCPDTBT) and the composite thin film of SiPCPDTBT:POSS-C60 indicated efficient electron transfer from SiPCPDTBT to POSS-C60 with inhibited back-transfer. BHJ PSCs made by SiPCPDTBT mixed with POSS-C60 yielded the power conversion efficiencies (PCEs) of 1.50%. Under the same operational conditions, PCEs observed from BHJ PSCs made by SiPCPDTBT mixed with [6,6]-phenyl-C61-butyric acid methyl ester were 0.92%. These results demonstrated that POSS-C60 is a potentially good electron acceptor for inverted BHJ PSCs.