Complementary Molecular Passivation of Multiple Surface Defects for Efficient and Stable Inverted Perovskite Solar Cells

A complementary passivation strategy employing the simultaneous use of phenylethylammonium iodide (PEAI) and ethylhydrazinoacetate hydrochloride (EHACl) is developed to mitigate multiple surface defects in perovskite films. PEAI mainly aims at vacancy defects and tends to induce quasi-2D/3D interface reconstruction, while rich Lewis base sites within EHACl enable it to selectively passivate Lewis acid defects such as undercoordinated Pb²⁺. Advanced nonadiabatic molecular dynamics simulations based on large supercell slabs of FAPbI₃ surface directly correlate the surface chemical interactions with nonradiative carrier lifetimes. The comprehensive theoretical-experimental analysis indicates that the 2D/3D interfaces induced by PEAI play a more crucial role in suppressing nonradiative recombination of carriers than localized defect healing of EHACl. The adsorption of EHACl leads to the downward shift of the energy band of the surface 2D layer, which results in a more favorable energy band alignment at the perovskite/electron transport layer interface to accelerate the electron extraction. The complementary passivation strategy remarkably improves the photovoltaic performance of perovskite solar cells (PSCs) with p-i-n architecture and leads to a champion power conversion efficiency of 24.6%. Moreover, the strategy notably enhances both operational and thermal stability of PSCs by healing multiple surface defects and forming a more robust interfacial layer.