Enhancing Chemical Bonding at Buried Interface Enables Improved Performance of Perovskite Solar Cell

The buried interface plays a vital role in determining the performance and durability of perovskite devices since it influences the charge movement, defects at the interface, and the growth of crystals. However, the self-assembled monolayer (SAM) generally leads to poor contact due to the weak intermolecular interactions. Here, an effective co-assembly monolayer method is reported by incorporating acetyl dl-carnitine chloride (ACL) into [4-(3,6-dimethyl-9H-carbazol-9yl) butyl] phosphonic acid (Me-4PACz) ethanol solution. The application of the ACL improves the coverage of SAM and simultaneously enhances the chemical bonding at the buried interface. As a result, the perovskite solar cells achieve a power conversion efficiency of 25.78% under simulated AM1.5 light conditions, maintaining more than 90% of their original efficiency after ≈600 h of operation at peak power.