Heterogeneity in transporting interfaces and perovskites poses a substantial challenge in improving the efficiency of perovskite solar cells from small to large scales, a key barrier to their commercial use. Here we find that the amorphous phases of self-assembling molecules (SAMs) can realize a more homogeneous perovskite growth. Hyperspectral analysis confirms a narrower and blueshifted photoluminescence peak distribution in perovskite/amorphous SAMs. Additionally, fluence-dependent time-resolved photoluminescence reveals a reduced trap-assisted recombination rate of 0.5 × 106 s−1 in amorphous-SAM-based perovskite films. This improvement translates to p–i–n structured perovskite solar cells achieving an efficiency of 25.20% (certified at 24.35%) over a one-square-centimetre area. These cells maintain nearly 100% efficiency after 600 h of 1-sun maximum power point tracking under the ISOS-L-1 protocol, and retain 90% of their initial efficiency after 1,000 h, as evaluated by the ISOS-T-2 protocol.