Enhancement of Gating Performance for Molecular Field‐Effect Transistors by Tuning Quantum Interference

Abstract Modification in molecular structure to tune quantum interference (QI) is an effective method to improve the gating performance of a single‐molecule field‐effect transistor. In this work, the gating efficiency can be significantly enhanced through modifying the orientation of a cyclopentadiene component in molecular backbone. When the five‐membered ring connects at C2 and C5 sites, constructive QI occurs between the HOMO and the LUMO. The conductance varies inconspicuous under different electrostatic potential with an ON/OFF current ratio 14.8 observed. In contrast, when the cyclopentadiene ring connects at C2 and C4 sites, under an appropriate electrostatic modulation, destructive QI takes place and results in a highly suppressed OFF‐state current, and consequently an enhanced ON/OFF current ratio (581.5) obtained. Electronic structural analysis reveals that this alternation in QI patterns originates from the activation or deactivation of one transmission pathway regulated by the location of the sp 3 hybridized carbon atom.