The self-assembled monolayer (SAM) between a perovskite and the electrode must provide both interfacial anchoring and hole transport. This Nature work finds that the new molecule has a smaller average coupling, yet achieves better transport because of more uniform packing and smaller energy-level fluctuations, showing that a single computational metric may not explain device performance. The authors designed a donor–acceptor–donor (D–A–D) resonant molecule, FMTPA-CPA, and used DFT and all-atom MD to connect the single molecule, the interface, and the assembled film, explaining why it can improve both efficiency and stability.