PenAAc-based interfacial passivation to reduce voltage loss and defect densities in lead-free perovskite solar cells

Tin-based perovskites are considered a promising alternative to lead-based perovskites due to their low toxicity and suitable optical bandgap. However, the defects and voltage loss issues severely limit their device performance. In this study, an interfacial passivation strategy based on pentylammonium acetate (PenAAc) was proposed in tin-based perovskite solar cells. The PenAAc-modified layer can effectively improve the perovskite film morphology, crystallinity, and hydrophobicity. Meanwhile, the introduction of the PenAAc layer can significantly inhibit carrier complexation and reduce the hysteresis effect in solar cells. By systematically analyzing the charge transport and compounding mechanisms, the PenAAc layer enhances the built-in electric field, improves the carrier separation and the carrier extraction efficiency, and reduces the defect density in the perovskite layer. The optimal tin-based perovskite solar cell achieved a power conversion efficiency of 7.0%. Moreover, the PenAAc-modified device maintained above 89% of its initial efficiency even after 1200 h storage in a nitrogen-filled glovebox.