Synergistic Crystallization Kinetics Modulation and Deep/Shallow Level Defect Passivation via an Organometallic Cobaltocenium Salt Toward High-Performance Inverted Perovskite Solar Cells

Numerous deep/shallow level defects generated at the surface/grain boundaries of perovskite during uncontrollable crystallization pose a formidable challenge to the photovoltaic performance of perovskite solar cells (PSCs). Herein, an organometallic cobaltocenium salt additive, 1-propanol-2-(1,2,3-triazol-4-yl) cobaltocenium hexafluorophosphate (PTCoPF₆), is incorporated into the perovskite precursor solution to regulate crystallization and minimize holistic defects for high-performance inverted PSCs. The cobaltocenium cations and PF₆⁻ in PTCoPF₆ stabilize the Pb-I framework and repair the shallow-level defects of positively and negatively charged vacancies in the perovskite. The N═N in the triazole ring of PTCoPF₆ can passivate the deep-level defects of uncoordinated lead. The interaction between PTCoPF₆ and perovskite materials delays perovskite nucleation and crystal growth, ensuring high-quality perovskite with large grains, and suppressing non-radiative recombination and ion migration. Therefore, the PTCoPF₆-incorporated PSC achieves an impressive power conversion efficiency of 25.03% and outstanding long-term stability. Unencapsulated and encapsulated PTCoPF₆-incorporated PSCs maintain 93% and 95% of their initial efficiencies under 85 °C storage in a nitrogen atmosphere for 1000 h and maximum power point tracking for nearly 1000 h, respectively. Synergistic crystallization kinetic modulation and deep/shallow level defect passivation with ionized metal-organic complex additives will become prevalent methods to improve the efficiency and stability of PSCs.