Polar Heterocyclic Molecule Assisted Co-Assembled Monolayers Mediate the NiOx/Perovskite Interface for High-Efficiency and Stable Inverted Perovskite Solar Cells

Abstract

(Self-assembled monolayers) SAMs are capable of improving the quality of perovskite and passivating defects, but their inhomogeneous layer formation hinders molecular connectivity and charge transport. To address these issues, a heteroarene molecule (benzo[c][1,2,5]oxadiazoe-5-boronic acid, BBOA) is chosen to form a co-assembled(Co-SAM) layer with MeO-2PACz to increase the coverage and defect inherent defects of Co-SAM layer on NiOx through π–π stacking interactions. Meanwhile, BBOA can form Pb–O bonds and O–H⋯I⁻ hydrogen bonds with the defects from the perovskite. Besides, the strong electron-withdrawing oxadiazole functionality deepens the molecular energy levels and redistributes the electronic environment, thereby optimizing the energy level alignment and charge extraction at the interface. As a result, BBOA-modified perovskite solar cells achieve a champion efficiency of 25.08%, superior to 23.62% for the NiOx/MeO-2PACz-based device, and respectively maintain 93.4% and 87.4% of its initial performance after 1200 hours at 25°C and after 672 hours at 65°C under N2 atmosphere of continuous operation without encapsulation.