Three birds with one stone: dual-interfaces and bulk co-passivation enable >21% efficiency of CsPbI3 solar cells with VOC of 1.27 V

Inorganic perovskite solar cells (IPSCs) have garnered significant research interest in recent years owing to their excellent light and thermal stability, as well as their potential applications in tandem solar cells. However, the power conversion efficiency (PCE) and stability of IPSCs are often compromised by residual lattice stress and numerous defects at interfaces and within the bulk material, which lead to severe nonradiative recombination of photogenerated carriers. To address these challenges, we developed a zero-dimensional supramolecular complex, (ETP) 2 SbCl 5 , serving as both a dual interface and bulk modifier to regulate the growth of inorganic CsPbI 3 perovskite films. The (ETP) 2 SbCl 5 modifier exhibits a unique spatial distribution: the ETP + cations preferentially anchor at the buried interface, passivating defects on both TiO 2 and perovskite surfaces, while Sb 3+ and Cl − ions diffuse into the perovskite bulk during annealing, effectively relieving residual lattice stress. Moreover, Cl − anions accumulate on the top surface of the CsPbI 3 film, passivating cation defects. Consequently, the (ETP) 2 SbCl 5 -modified CsPbI 3 IPSC achieves a high-quality active layer with significantly reduced defects and suppressed energy loss, an impressive PCE of 21.71% and a high open circuit voltage of 1.27 V, remaining 97.4% of their initial efficiency after 500 h of continuous maximum power point (MPP) tracking.