Fluorinated fulleropyrrolidine as universal electron transport material for organic-inorganic and all-inorganic perovskite solar cells.

[6,6]-Phenyl-C 61 -butyric acid methylester (PC 61 BM) has been widely used as electron transport material (ETM) for both organic-inorganic hybrid and all inorganic perovskite solar cells (PeSCs) with inverted structure. However, PC 61 BM still remains to be improved due to its low electrical conductivity and inferior passivation effect towards perovskite. In this work, we synthesize two perfluorophenyl-substituted fulleropyrrolidines, 2-(perfluorophenyl)-5-phenyl-C 60 -fulleropyrrolidine (FP-i) and 2,5-bis-(perfluorophenyl)-C 60 -fulleropyrrolidine (FP-ii) via a modified 1,3-dipolar cycloaddition reaction. FP-i and FP-ii are introduced into inverted PeSCs based on organic-inorganic hybrid and all inorganic perovskites (CH 3 NH 3 PbCl 3-x I x and CsPbI 2 Br) as ETMs. The PeSCs based on FP-i and FP-ii display good photovoltaic performance and device stability, which are superior or comparable to those with PC 61 BM. The mechanism studies reveal that FP-i and FP-ii possess higher electrical conductivity, more significant passivation capacity and enhanced hydrophobicity but slightly lower low unoccupied molecular orbital (LUMO) levels. These results suggest that FP-i and FP-ii are universal ETMs for both organic-inorganic hybrid and all inorganic PeSCs, which are better or comparable to conventional ETM of PC 61 BM. Image 1 • We design and synthesize two perfluorophenyl-substituted fulleropyrrolidines (FP-i and FP-ii). • FP-i and FP-ii are introduced into hybrid and all-inorganic PeSCs, respectively, as ETMs. • The PeSCs with FP-i and FP-ii display good photovoltaic performance. • FP-i and FP-ii outperform or comparable to conventional ETM of PC 61 BM. [ABSTRACT FROM AUTHOR]