Balancing Disparate Crystallization Kinetics in Sn-Pb Perovskites Using a Sulfaguanidine Additive for...

Mixed tin-lead (Sn-Pb) perovskites hold significant promise for efficient single-junction and tandem solar cells due to their tunable narrow bandgaps, but their performance is often hindered by disparate crystallization kinetics between Sn and Pb precursors and Sn²⁺ instability. Herein, we introduce sulfaguanidine (SG) as a multifunctional additive. SG utilizes its dual sulfonyl (S═O) groups to coordinate with Sn²⁺/Pb²⁺ ions, crucially balancing their disparate crystallization rates. This kinetically harmonized growth, confirmed by in situ monitoring, significantly enhances film quality, suppressing Sn⁴⁺ formation, reducing defects, and prolonging carrier lifetimes. Consequently, SG-modified inverted devices achieve a champion efficiency of 22.24% (vs 19.75% control) with improved stability. This work presents an effective coordination-driven strategy for kinetic harmonization, overcoming a key bottleneck and advancing efficient, stable Sn-Pb photovoltaics.