Single-molecule field effect and conductance switching driven by electric field and proton transfer

Abstract

Single-molecule junctions (SMJs) offer a novel strategy for miniaturization of electronic devices. In this work, we realize a graphene-porphyrin-graphene SMJ driven by electric field and proton transfer in two configurations. In the transistor configuration with ionic liquid gating, an unprecedented field-effect performance is achieved with a maximum on/off ratio of ~4800 and a gate efficiency as high as ~179 mV/decade in consistence with the theoretical prediction. In the other configuration, controllable proton transfer, tautomerization switching, is directly observed with bias dependence. Room temperature proton transfer leads to a two-state conductance switching, and more precise tautomerization is detected, showing a four-state conductance switching at high bias voltages and low temperatures. Such an SMJ in two configurations provides new insights into not only building multifunctional molecular nanocircuits toward real applications but also deciphering the intrinsic properties of matters at the molecular scale.

Dipole-improved gating of azulene-based single-molecule transistors

“…[5][6][7] Due to the inherently small size of the single-molecule FET, it has the potential to extend Moore's law to the single-molecule level, breaking the development bottleneck of device miniaturization. [8][9][10][11][12] Meanwhile, it is also a powerful tool for exploring quantum transport and novel physical phenomena. [13][14][15][16][17][18][19] Therefore, single-molecule FETs have been widely studied.…”

“…A lot of work has been done to overcome this challenge. 6,12,[23][24][25] A typical example is the ionic liquid gate, 26,27 which modulates charge transport of the single-molecule FETs by utilizing the electrical double layer of ionic dielectrics. Since the thickness of the electrical double layer is at the molecular level and the capacitance is large, the electric field applied to the molecule can be quite strong.…”

Photoconductance from the Bent-to-Planar Photocycle between Ground and Excited States in Single-Molecule Junctions

“…This suggested that the maximum photoconductance was achieved under continuous irradiation of 340 nm around the absorption maxima in the range of 295–500 nm. However, an external electric field has typically exerted noteworthy effects on the conductance switching of single-molecule devices. , With this in mind, we carried out conductance measurements for DPAC-SMe under the same conditions except for the application of a higher bias voltage of 180 mV. The conductance, which was determined from the corresponding 2D and 1D conductance histograms (see Figure S4), increased from ∼10 –4.50 G 0 (∼2.5 nS) to ∼10 –4.02 G 0 (∼7.4 nS) under continuous 340 nm light irradiation and was restored immediately after ceasing of the light, showing identical photoconductance compared to that applying a lower voltage.…”

Design of Pyrrole-Based Gate-Controlled Molecular Junctions Optimized for Single-Molecule Aflatoxin B1 Detection

“…It is a three-terminal device in which the drain current, , is modulated by the gate voltage, . Usually, in MolFETs, the molecular channel is electrostatically coupled to solid-state gate electrodes [ 19 , 44 , 60 , 61 ], but electrochemical coupling also is possible with ionic liquid-gated systems [ 62 , 63 ]. Solid-state gate electrodes require additional nanofabrication steps when compared to two-terminal single-molecule devices.…”