TY - JOUR
T1 - Controlled Hysteresis of Conductance in Molecular Tunneling Junctions
AU - Park, Junwoo
AU - Kodaimati, Mohamad S.
AU - Belding, Lee
AU - Root, Samuel E.
AU - Schatz, George C.
AU - Whitesides, George M.
N1 - Funding Information:
This work was supported by the National Science Foundation (NSF, CHE-18083681 to G.M.W.) and by NSF through the Harvard University Materials Research Science and Engineering Center (MRSEC, DMR-1420570, and DMR-2011754). Sample characterization was performed in part at the Center for Nanoscale Systems (CNS) at Harvard University, a member of the National Nanotechnology Infrastructure Network (NNIN), which is supported by the National Science Foundation (ECS-0335765). DFT calculations were run on the FASRC Cannon cluster supported by the FAS Division of Science Research Computing at Harvard University. J.P. acknowledges the National Research Foundation of Korea (NRF) grant funded by the Korea government (2022R1C1C1006638), and the Sogang University Research Grant of 2021 (202110030.01). M.S.K. acknowledges the Simons Foundation, Award 290364FY21, for partial salary support. L.B. acknowledges fellowship support from NSERC, Canada. G.C.S. acknowledges the Department of Energy, Office of Basic Energy Sciences, Grant DE-SC0000989. We thank Victoria E. Campbell and Hyo Jae Yoon for their discussions.
Publisher Copyright:
© 2022 American Chemical Society. All rights reserved.
PY - 2022/3/22
Y1 - 2022/3/22
N2 - The problem this paper addresses is the origin of the hysteretic behavior in two-terminal molecular junctions made from an EGaIn electrode and self-assembled monolayers of alkanethiolates terminated in chelates (transition metal dichlorides complexed with 2,2′-bipyridine; BIPY-MCl2). The hysteresis of conductance displayed by these BIPY-MCl2junctions changes in magnitude depending on the identity of the metal ion (M) and the window of the applied voltage across the junction. The hysteretic behavior of conductance in these junctions appears only in an incoherent (Fowler-Nordheim) tunneling regime. When the complexed metal ion is Mn(II), Fe(II), Co(II), or Ni(II), both incoherent tunneling and hysteresis are observed for a voltage range between +1.0 V and -1.0 V. When the metal ion is Cr(II) or Cu(II), however, only resonant (one-step) tunneling is observed, and the junctions exhibit no hysteresis and do not enter the incoherent tunneling regime. Using this correlation, the conductance characteristics of BIPY-MCl2junctions can be controlled. This voltage-induced change of conductance demonstrates a simple, fast, and reversible way (i.e., by changing the applied voltage) to modulate conductance in molecular tunneling junctions.
AB - The problem this paper addresses is the origin of the hysteretic behavior in two-terminal molecular junctions made from an EGaIn electrode and self-assembled monolayers of alkanethiolates terminated in chelates (transition metal dichlorides complexed with 2,2′-bipyridine; BIPY-MCl2). The hysteresis of conductance displayed by these BIPY-MCl2junctions changes in magnitude depending on the identity of the metal ion (M) and the window of the applied voltage across the junction. The hysteretic behavior of conductance in these junctions appears only in an incoherent (Fowler-Nordheim) tunneling regime. When the complexed metal ion is Mn(II), Fe(II), Co(II), or Ni(II), both incoherent tunneling and hysteresis are observed for a voltage range between +1.0 V and -1.0 V. When the metal ion is Cr(II) or Cu(II), however, only resonant (one-step) tunneling is observed, and the junctions exhibit no hysteresis and do not enter the incoherent tunneling regime. Using this correlation, the conductance characteristics of BIPY-MCl2junctions can be controlled. This voltage-induced change of conductance demonstrates a simple, fast, and reversible way (i.e., by changing the applied voltage) to modulate conductance in molecular tunneling junctions.
KW - EGaIn junction
KW - charge transport
KW - hysteresis in conductance
KW - molecular electronics
KW - molecular tunneling junctions
KW - quantum tunneling
KW - self-assembled monolayers (SAMs)
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U2 - 10.1021/acsnano.1c10155
DO - 10.1021/acsnano.1c10155
M3 - Article
C2 - 35230085
AN - SCOPUS:85126098709
SN - 1936-0851
VL - 16
SP - 4206
EP - 4216
JO - ACS nano
JF - ACS nano
IS - 3
ER -