Homogenizing SAM deposition via seeding -OH groups for scalable fabrication of perovskite solar cells

Self-assembled monolayers (SAMs) play a significant role in the rapidly advancing inverted perovskite solar cells (PSCs). Additional metal oxide or molecular incorporations are widely adopted to ameliorate their incomplete and uneven deposition on substrates, where the underlying binding situations between SAMs and substrates are vital for further optimization but remain unclear. Here, we compared the bonding types between SAMs and metal oxides from a theoretical view and concluded that SAMs preferably form strong chemical bonds of -P-O-Sn by reacting with hydroxyl groups (-OH) on metal oxides for stable adsorption. We further proposed a simple yet effective strategy, named seeding -OH groups via hydrogen peroxide (H₂O₂)/ultraviolet bath, to strengthen and homogenize SAM deposition on substrates, yielding superior buried interface contact and high-quality perovskite films. Benefiting from the promotions, the resulted PSCs realized the champion efficiency of 26.19%, and 24.68% and 21.77% during their scalable fabrications with the areas of 1.21 and 13.8 cm² (minimodules, active area), surpassing the bare ones with inferior scalability. Moreover, the large-area device maintained over 90% of their initial efficiency after the ISOS-L-3 test for 1000 h.