Highly Efficient and Stable Inverted Polymer Solar Cells Integrated with a Cross-Linked Fullerene Material as an Interlayer

摘要

A novel PCBM-based n-type material, [6,6]-phenyl-C61-butyric styryl dendron ester (PCBSD),nfunctionalized with a dendron containing two styryl groups as thermal cross-linkers, has been rationallyndesigned and easily synthesized. In situ cross-linking of PCBSD was carried out by heating at a lowntemperature of 160 °C for 30 min to generate a robust, adhesive, and solvent-resistant thin film. This crosslinkednnetwork enables a sequential active layer to be successfully deposited on top of this interlayer tonovercome the problem of interfacial erosion and realize a multilayer inverted device by all-solution processing.nAn inverted solar cell device based on an ITO/ZnO/C-PCBSD/P3HT:PCBM/PEDOT:PSS/Ag configurationnnot only achieves enhanced device characteristics, with an impressive PCE of 4.4%, but also exhibits annexceptional device lifetime without encapsulation; it greatly outperforms a reference device (PCE ) 3.5%)nbased on an ITO/ZnO/P3HT:PCBM/PEDOT:PSS/Ag configuration without the interlayer. This C-PCBSDninterlayer exerts multiple positive effects on both P3HT/C-PCBSD and PCBM/C-PCBSD localizednheterojunctions at the interface of the active layer, including improved exciton dissociation efficiency, reducedncharge recombination, decreased interface contact resistance, and induction of vertical phase separationnto reduce the bulk resistance of the active layer as well as passivation of the local shunts at the ZnOninterface. Moreover, this promising approach can be applied to another inverted solar cell, ITO/ZnO/CPCBSDPCPDTBT:PC71BM/PEDOT:PSS/Ag, using PCPDTBT as the p-type low-band-gap conjugatednpolymer to achieve an improved PCE of 3.4%. Incorporation of this cross-linked C60 interlayer could becomena standard procedure in the fabrication of highly efficient and stable multilayer inverted solar cells.