Poly(ethylene glycol) modified [60]fullerene as electron buffer layer for high-performance polymer solar cells

A poly(ethylene glycol) end caped fullerene derivative, PEGN-C-60, is used as electron buffer layer (EBL) in polymer solar cells (PSCs). Three donor: acceptor blends, namely P3HT:PCBM, PBDTTT-C:PC70BM, and PBDTTT-C-T:PC70BM, are employed to test the behavior of PEGN-C-60 as EBL. The optimized power conversion efficiencies of the three systems reach 3.84%, 6.22%, 7.45%, respectively, which are slightly higher than that of their corresponding devices with metal Ca as EBL and much higher than that of their devices without any EBLs. Our results indicate that exploring EBLs based on fullerene derivatives might be an efficient way in finding functional solution-processable EBLs for high-performance PSCs. (C) 2013 AIP Publishing LLC