Enhanced Efficiency and Stability of Inverted Perovskite Solar Cells via Isomerization Engineering of Self-Assembled Monolayers.

Abstract

Carbazole-based SAMs show great promise as interfacial modifiers in inverted perovskite solar cells (PSCs). Their large dipole moments and covalent binding capabilities suppress charge recombination and enhance device stability. We designed two isomeric carbazole SAMs (EPACz and PPACz) by adjusting the phenyl ring position. PPACz exhibits a higher dipole moment (2.60 D versus 1.77 D for EPACz) and a narrower HOMO-LUMO gap (2.39 eV), enabling superior hole extraction. PPACz-based devices achieved an excellent PCE of 26.1% (versus 22.0% for EPACz), with 23.5% efficiency for 1 cm2 devices. The stronger tridentate anchoring of PPACz to ITO (compared with EPACz) improves interfacial stability. Unencapsulated devices retained over 90% of their initial efficiency after 540 h, demonstrating exceptional durability. This work provides key insights for designing high-performance SAMs in perovskite photovoltaics.