FAPbI3-based perovskite solar cells (PSCs) are more efficient than their MAPbI3 counterparts, but their fabrication in air still faces more severe stability and reproducibility challenges. The underlying problem lies in the residual hygroscopic DMSO disrupts the perovskite crystallization by absorbing moisture, and an excessively rapid reaction between FAI and PbI2 causing incomplete conversion and PbI2 residue. Here, we introduce thiacetazone additive into the PbI2 precursor solution. This additive interacts with PbI2 to significantly reduce PbI2·xDMSO complexes and form a mesoporous film conducive to the subsequent permeation of organic ammonium salt, while simultaneously interacting with FAI to moderate the reaction rate with PbI2. This multifunctional additive improves crystallization, substantially reduces residual PbI2, and effectively passivates defects in the perovskite film. Consequently, the optimized FAPbI3-based PSCs achieve a record power conversion efficiency (PCE) of 26.52%-the highest value for air-processed n-i-p PSCs reported so far. When the PSCs are fabricated in a high-humidity atmosphere (70% RH), the PSCs still achieve a high PCE of 23.24%. Unencapsulated devices retain 92% of their initial PCE after 180 days in air (30-40% RH). This strategy provides a promising route to achieve efficient and storage-stable PSCs under ambient humidity.
Li et al. (Mon,) studied this question.