Cross-Linkable, Solvent-Resistant Fullerene Contacts for Robust and Efficient Perovskite Solar Cells with Increased J SC and V OC .

The active layers of perovskite solar cells are also structural layers and are central to ensuring that the structural integrity of the device is maintained over its operational lifetime. Our work evaluating the fracture energies of conventional and inverted solution-processed MAPbI ₃ perovskite solar cells has revealed that the MAPbI ₃ perovskite exhibits a fracture resistance of only ∼0.5 J/m ² , while solar cells containing fullerene electron transport layers fracture at even lower values, below ∼0.25 J/m ² . To address this weakness, a novel styrene-functionalized fullerene derivative, MPMIC ₆₀ , has been developed as a replacement for the fragile PC ₆₁ BM and C ₆₀ transport layers. MPMIC ₆₀ can be transformed into a solvent-resistant material through curing at 250 °C. As-deposited films of MPMIC ₆₀ exhibit a marked 10-fold enhancement in fracture resistance over PC ₆₁ BM and a 14-fold enhancement over C ₆₀ . Conventional-geometry perovskite solar cells utilizing cured films of MPMIC ₆₀ showed a significant, 205% improvement in fracture resistance while exhibiting only a 7% drop in PCE (13.8% vs 14.8% PCE) in comparison to the C ₆₀ control, enabling larger V _OC and J _SC values. Inverted cells fabricated with MPMIC ₆₀ exhibited a 438% improvement in fracture resistance with only a 6% reduction in PCE (12.3% vs 13.1%) in comparison to those utilizing PC ₆₁ BM, again producing a higher J _SC .