Dimeric Self‐Assembled Molecules Modulate Phase Homogeneity and Anchoring Stability for High‐Performance Perovskite Solar Cells

Phase‐homogenized self‐assembled molecules (SAMs) provide a key pathway for advancing the scale‐up fabrication of p‐i‐n perovskite solar cells (PSCs). However, enhancing the thermal stability of SAMs whilst addressing phase homogeneity remains a great challenge. Herein, two dimeric SAMs are reported, named Ph‐BCzPA and Th‐BCzPA, comprising monomer BCzPA ((4‐(7 H ‐benzo[c]carbazol‐7‐yl)butyl) phosphonic acid) unit bridged by 1,4‐phenyl and a 2,5‐thienyl groups, respectively. Combining molecular dynamics simulations and experimental results, it is demonstrated that both Ph‐BCzPA and Th‐BCzPA form a more homogeneous morphology compared to its monopodal counterpart, BCzPA. Time‐of‐flight secondary‐ion mass spectroscopy and X‐ray photoelectron spectroscopy further reveal the excellent morphological stability of Ph‐BCzPA under thermal ageing conditions. When applied in p‐i‐n PSCs, the Ph‐BCzPA controlled device achieves a champion power conversion efficiencies (PCE) of 26.33% with excellent reproducibility. Remarkably, the device retains 93% of its initial PCE after 500 hours of maximum power point tracking at 65 °C (ISOS‐L‐2I protocol) and 90% of its initial PCE after 2 000 hours of thermal ageing at 85 °C with a relative humidity of 60%–70% (ISOS‐D‐2 protocol), demonstrating superior operational and thermal stability.