Cross-linkable styrene-functionalized fullerenes as electron-selective contacts for robust and efficient perovskite solar cells

Styrene functionalized fullerene derivatives have been designed for use as electron-selective contacts in perovskite solar cells. Unlike films of PC61BM and C60 fullerene, films of these styrene-functionalized fullerenes (SFFs) can be transformed into a solvent resistant material through thermal curing. Conventional-geometry perovskite solar cells utilizing cured and uncured thin films of SFFs on titania were fabricated and tested for PCE and fracture resistance, and compared to cells employing C60. These cells displayed significant improvements in the fracture resistance (> 200 %) while exhibiting only a 7% drop in PCE (13.8 % vs 14.8 % PCE), with larger VOC and JSC values in comparison to the C60 control cell. Inverted cells fabricated with SFFs displayed an even greater increase in fracture resistance (> 400 %) with only a 6 % reduction in PCE (12.3 % vs 13.1 %) in comparison to those utilizing PC61BM.