• • The (ETP)2SbCl5-modified CsPbI3 solar cell achieves a PCE of 21.71% and a VOC of 1.27 V, representing a significant improvement over control devices (typically <20% PCE). This efficiency gain is critical for commercial viability, as it approaches the theoretical limit for single-junction cells and enhances competitiveness against silicon.
• • The device retains 97.4% of its initial PCE after 500 h of continuous maximum power point (MPP) tracking, demonstrating exceptional operational stability. This addresses the chronic instability of perovskite solar cells, a key barrier to commercialization.
• • The dual-interface and bulk co-passivation strategy reduces nonradiative recombination, as evidenced by the high VOC (1.27 V) close to the Shockley-Queisser limit for a 1.7 eV bandgap. This indicates minimized energy losses, which is essential for achieving high efficiency.
• • The spatial distribution of (ETP)2SbCl5 components—ETP+ at the buried interface, Sb3+/Cl− in the bulk, and Cl− on the top surface—provides a multi-level defect passivation mechanism. This holistic approach addresses defects at all critical regions, offering a blueprint for future interface engineering in perovskite solar cells.