Molecule-Assisted Dispersion of Self-Assembled Monolayers for High-Efficiency and Stable Perovskite Solar Cells

Self-assembled monolayers (SAMs) are widely used in inverted perovskite solar cells (PSCs) due to their high hole mobility, excellent interfacial modification capability, and low-cost fabrication processes. However, conventional SAMs suffer from molecular aggregation during film formation, leading to non-uniform and low coverage issues, which ultimately hinder the enhancement of PSCs performance. Herein, this work presents a strategy to tackle this challenge through the modification of [4-(3,6-dimethyl-9H-carbazol-9-yl)butyl]phosphonic acid (Me-4PACz) with O-Phospho-L-tyrosine (OPLt) molecules. The aggregation of Me-4PACz molecules is suppressed through disrupting Me-4PACz dimers and reducing the intermolecular π-π stacking, while the anchoring sites for the SAM layer on the NiO_x substrate are optimized, facilitating enhanced interfacial contact and consequent perovskite crystallization. Eventually, PSCs based on the Co-SAM show a performance improvement, with a power conversion efficiency (PCE) of 26.03%. Meanwhile, the device stability has been effectively enhanced, with the efficiency retaining 81.90% of its initial value after 1200 h of continuous one-sun illumination. This work focused on the coverage and film quality of hole transport layers and demonstrated a molecule-assisted dispersion strategy toward high-efficiency and stable PSCs.