Synergistic regulation of crystallization and buried-interface in Cs x FA 1-x PbI 3 perovskite photovoltaics using a multifunctional sulfonyl-ammonium additive

Abstract

The fabrication of high-quality Cs x FA 1-x PbI 3 -based perovskite films is often limited by inhomogeneous crystallization and concomitant numerous defects. Here, we introduce 2-aminoethylmethylsulfone hydrochloride (AEMS) as a multifunctional ligand into the perovskite precursor solution to mitigate these issues. It is demonstrated that the O=S=O and NH 3 ⁺ groups in AEMS strongly interact with perovskite components, broadening the processing window and promoting preferentially (100)oriented crystal growth, which significantly enhances the crystallinity of Cs x FA 1-x PbI 3 films. Furthermore, AEMS spontaneously aggregates at the buried interface, where it selectively passivates interfacial defects, optimizes energy level alignment, and suppresses nonradiative recombination. As a result, Cs 0.05 FA 0.95 PbI 3 -based inverted perovskite solar cells achieve a power conversion efficiency (PCE) of 26.91% (certified 26.80%). The strategy also demonstrates excellent adaptability, yielding outstanding PCEs of 23.24% for mini-modules (aperture area of 11.1 cm 2 ) and 24.90% for flexible devices. Crucially, the encapsulated devices maintain 93% of their initial PCEs after 2,500 h of 1-sun operation at 65 °C in ambient air.