Conjugated polydentate ligand buffering for buried Interface passivation in inverted perovskite solar cells

In inverted perovskite solar cells, defect states at the buried interface, especially the undesirable direct contact between ITO and perovskite, seriously restrict further improvements in device performance. In this study, a conjugated polydentate ligand buffering strategy was proposed to introduce a multifunctional passivation molecule 2,3,5,6-tetrafluoro-4-mercaptobenzoic acid (TFMBA) between the MeO-2PACz hole transport layer and the perovskite layer. The ligands effectively anchor the exposed ITO substrate, repairing the defect area caused by uneven coverage of the hole transport layer, and eliminating harmful ITO/perovskite direct contact; Moreover, it forms coordination bonds and hydrogen bonds with uncoordinated lead ions and organic cations to achieve a comprehensive passivation of various ion defects at the buried bottom interface. This strategy suppresses non-radiative recombination, reduces voltage loss, and promotes high-quality crystallization at the bottom of the perovskite. Finally, the device based on TFMBA modification achieved an optimal photoelectric conversion efficiency of 25.61% and exhibited excellent performance reproducibility.