Irrelevant Role of Level‐Electrode Coupling Asymmetry in Driving Rectification in Molecular Tunnel Junctions: Decisive Experimental Evidence from Junctions with Dissimilar Electrodes

ABSTRACT Current rectification in molecular junctions inherently requires broken forward‐backward symmetry. A key question is whether asymmetric electrode‐molecule coupling significantly drives rectification in practical molecular electronics. To address this, previously explored only theoretically, we used conducting probe atomic force microscopy (CP‐AFM) to fabricate molecular junctions with symmetric molecules and dissimilar electrodes (Ag, Au, Pt). Using complementary benchmark molecular systems—saturated alkyl chains (featuring localized electrons) and oligophenyls (with delocalized electrons), we demonstrate that metal‐molecule contact asymmetry does not significantly contribute to rectification, thereby discarding a theoretical formula that has retained undue consideration in the molecular electronics community and continues to be presented as an open question under debate. This assumption‐free experimental finding provides crucial guidance for rationally designing high‐performance molecular rectifiers.