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Abstract The past decade has witnessed the rapid increasement in power conversion efficiency of perovskite solar cells (PSCs). However, serious ion migration hampers their operational stability. Although dopants composed of varied cations and anions are introduced into perovskite to suppress ion migration, the impact of cations or anions is not individually explored, which hinders the evaluation of different cations and further application of doping strategy. Here we report that a special group of sulfonic anions (like CF 3 SO 3 − ) successfully introduce alkaline earth ions (like Ca 2+ ) into perovskite lattice compared to its halide counterparts. Furthermore, with effective crystallization regulation and defect passivation of sulfonic anions, perovskite with Ca(CF 3 SO 3 ) 2 shows reduced PbI 2 residue and metallic Pb 0 defects; thereby, corresponding PSCs show an enhanced PCE of 24.95%. Finally by comparing the properties of perovskite with Ca(CF 3 SO 3 ) 2 and FACF 3 SO 3 , we found that doped Ca 2+ significantly suppressed halide migration with an activation energy of 1.246 eV which accounts for the improved operational stability of Ca(CF 3 SO 3 ) 2 -doped PSCs, while no obvious impact of Ca 2+ on trap density is observed. Combining the benefits of cations and anions, this study presents an effective method to decouple the effects of cations and anions and fabricate efficient and stable PSCs.
Hu et al. (Fri,) studied this question.