Enhancing the Growth Quality of Perovskite on MeO-2PACz by Introducing a Phenethylammonium Seed Layer

Self-assembled monolayers (SAMs) are efficient hole transport layers, but their hydrophobicity adversely affects the morphology of perovskite thin films. We improve the wettability of the SAM by introducing phenethylammonium iodide (PEAI) at the SAM/perovskite interface. The perovskite films coated on PEAI-treated SAM have less strain, larger grains, and longer carrier recombination lifetimes. Solar cells with PEAI have a higher short-circuit current and fill factor, so the champion power conversion efficiency increases from 19.27% to 21.76%. These devices also show a better charge collection efficiency across the visible spectrum. Photoelectromagnetic and photoconductivity measurements show that PEAI reduces bulk recombination velocity, improves carrier diffusion length, and enhances bulk carrier lifetime.