z‑Piezo Pulse-Modulated STM Break Junction: Toward Single-
Molecule Rectifiers with Dissimilar Metal Electrodes
Author(s):
Xiao-Mei Li, Ya-Hao Wang, Jing-Wen Seng, Ju-Fang Zheng, Rui Cao, Yong Shao, Jing-Zhe Chen
Jian-Feng Li, Jian-Feng Li, Xiao-Shun Zhou, Bing-Wei Mao
Journal:
ACS Applied Materials & Interfaces
Year:
2021
Volume:
13
Pages
8656–8663
DOI:
10.1021/acsami.0c21435
Abstract:
Fabricating single-molecule junctions with asymmetric metal electrodes
is significant for realizing single-molecule diodes, but it remains a big challenge. Herein,
we develop a z-piezo pulse-modulated scanning tunneling microscopy break junction
(STM-BJ) technique to construct a robust asymmetric junction with different metal
electrodes. The asymmetric Ag/BPY-EE/Au single-molecule junctions exhibit a middle
conductance value in between those of the two individual symmetric metal electrode
junctions, which is consistent with the order of calculated energy-dependent
transmission coefficient T(E) of the asymmetric junctions at EF. Furthermore, the
single-molecule conductance of Ag/BPY-EE/Au decreases by about 70% when
reversing the bias voltage from 100 to −100 mV, and a clear asymmetric I−V feature at
the single-molecule level is observed for these junctions. This rectifying behavior could
be ascribed to a different interfacial coupling of molecules at the two end electrodes,
which is confirmed by the different displacement of T(E) at the two bias voltages.
Other asymmetric junctions exhibit similar rectifying behavior. The current work provides a feasible way to fabricate hybrid junctions
based on asymmetric metal electrodes and investigate their electron transport toward the design of molecular rectifiers.