Incorporating C₆₀ as Nucleation Sites Optimizing PbI₂ Films To Achieve Perovskite Solar Cells Showing Excellent...

To achieve high-quality perovskite solar cells (PSCs), the morphology and carrier transportation of perovskite films need to be optimized. Herein, C₆₀ is employed as nucleation sites in PbI₂ precursor solution to optimize the morphology of perovskite films via vapor-assisted deposition process. Accompanying the homogeneous nucleation of PbI₂, the incorporation of C₆₀ as heterogeneous nucleation sites can lower the nucleation free energy of PbI₂, which facilitates the diffusion and reaction between PbI₂ and organic source. Meanwhile, C₆₀ could enhance carrier transportation and reduce charge recombination in the perovskite layer due to its high electron mobility and conductivity. In addition, the grain sizes of perovskite get larger with C₆₀ optimizing, which can reduce the grain boundaries and voids in perovskite and prevent the corrosion because of moisture. As a result, we obtain PSCs with a power conversion efficiency (PCE) of 18.33% and excellent stability. The PCEs of unsealed devices drop less than 10% in a dehumidification cabinet after 100 days and remain at 75% of the initial PCE during exposure to ambient air (humidity > 60% RH, temperature > 30 °C) for 30 days.