Molecular electronics offers the potential for the miniaturization of electronic devices. One vital question is how small the device can achieve while retain the electronic functionality, among which the rectification behaviour is imperative. It has been generally expected that a molecular rectifier should be longer than one nanometer in length. Otherwise, the tunneling leakage current would overwhelm the function of the molecular component itself. To date it is a challenge to design the molecular rectifier at the sub-nanometer scale.
Nevertheless, destructive quantum interference exhibits a unique quantum mechanism that is length-independent, which provides the opportunity to modulate the electronic performance with a very small size. Moreover, the anti-resonance transmission associated with destructive quantum interference leads to sharp conductance variation with the change of carrier energy, which could significantly modulate the electronic performance of molecular junctions at the sub-nanometer scale.
Recently, Prof. Wenjing Hong in Xiamen University and Prof. Haiping Xia in Southern University of Science and Technology have designed a sub-nanometer molecular rectifier of ~0.76 nm with a combined destructive σ-interference and asymmetric supramolecular interaction methods. The destructive σ-interference of 1,4-diazabicyclo[2.2.2]octane (DABCO) suppresses the tunneling leakage to ensure a large slope in the transmission function around the Fermi level. And, the asymmetric supramolecular interaction generates the asymmetric shifting of electrode energy. The two factors were found to be indispensable for the achievement of rectification behaviour at the sub-nanometer scale in this work.
See the article: Huang L-F, Zhou Y, Chen Y-R, Ye J-Y, Liu J-Y, Xiao Z-Y, Tang C, Xia H-P, Hong W-J. Sub-nanometer supramolecular rectifier based on the symmetric building block with destructive σ-interference. Sci. China Chem., 2021, 64, 1426-1433.
https://link.springer.com/article/10.1007/s11426-021-1086-4
Science China Chemistry