Interface modification of the electron transport layer via a dry-processed conformal MgSnO_xinterlayer in inorganic CsPbI₃perovskite solar cells for enhanced performance and stability

To improve the performance of perovskite solar cells (PSC), we fabricate low-temperature SnO₂-based CsPbI₃ PSCs and introduce an MgSnO_x interlayer via atomic layer deposition (ALD) between the spin-coated SnO₂ electron transport layer and fluorine-doped tin oxide (FTO) substrate. Adjustment of the Mg content in the MgSnO_x interlayer results in a favorable energy band alignment with the perovskite active layer of the PSC. Consequently, the introduction of the ALD-processed MgSnO_x interlayer reduces leakage current, suppresses carrier recombination, and improves carrier extraction. Furthermore, the MgSnO_x interlayer improves the quality of the perovskite layer; consequently, the power conversion efficiency (PCE) of the fabricated PSCs increases from 13.42% to 18.50%, recording one of the highest PCEs among SnO₂-based CsPbI₃ PSCs. Introduction of the MgSnO_x interlayer also reduces hysteresis by approximately 50%. The unencapsulated PSC with the MgSnO_x interlayer retains 98% of its initial efficiency after 717 h of storage in air under a relative humidity of 18–30% at room temperature and 90% of its initial efficiency after 200 h in an N₂ atmosphere under 1 sun illumination. This study presents an effective method for optimizing the performance of SnO₂-based CsPbI₃ perovskite solar cells, ensuring both long-term stability and high efficiency.