Modulation of the Dirac Point Voltage of Graphene by Ion-Gel Dielectrics and Its Application to Soft Electronic Devices

Abstract

We investigated systematic modulation of the Dirac point voltage of graphene transistors by changing the type of ionic liquid used as a main gate dielectric component. Ion gels were formed from ionic liquids and a non-triblock-copolymer-based binder involving UV irradiation. With a fixed cation (anion), the Dirac point voltage shifted to a higher voltage as the size of anion (cation) increased. Mechanisms for modulation of the Dirac point voltage of graphene transistors by designing ionic liquids were fully understood using molecular dynamics simulations, which excellently matched our experimental results. It was found that the ion sizes and molecular structures play an essential role in the modulation of the Dirac point voltage of the graphene. Through control of the position of their Dirac point voltages on the basis of our findings, complementary metal-oxide-semiconductor (CMOS)-like graphene-based inverters using two different ionic liquids worked perfectly even at a very low source voltage (V(DD) = 1 mV), which was not possible for previous works. These results can be broadly applied in the development of low-power-consumption, flexible/stretchable, CMOS-like graphene-based electronic devices in the future.

Lateral Graphene p–n Junctions Realized by Nanoscale Bipolar Doping Using Surface Electric Dipoles and Self‐Organized Molecular Anions

“…In order to achieve localized p‐doping on graphene, the BMP‐TFSI ionic liquid was casted on the GFET channel to form a double‐gated GFET with the ionic liquid as the top gate. Molecular ions in the ionic liquids may self‐organize on graphene to achieve the desired p‐ or n‐doping to graphene . The molecular weight of cations and anions is a key control parameter, and the p‐doping can be achieved by selecting ionic liquids with anion molecular weight larger than the cation's one, which is the case in the BMP‐TFSI.…”

Highly Flexible and High‐Performance Complementary Inverters of Large‐Area Transition Metal Dichalcogenide Monolayers

“…To evaluate our results, we compare the obtained gain with other literature. Figure displays a summary of the supply voltage versus the voltage gain for inverters based on 2D materials, including TMDCs, black phosphorene, and graphene . In particular, as shown in Figure , TMDC‐based inverters outperform those of phosphorene and graphene .…”

“…Summary of the reported 2D‐material‐based inverters. Voltage gain versus supply voltage is plotted with the literature results of TMDCs, black phosphorene, and graphene . Black diamonds, brown squares, and gray circles indicate inverters fabricated from various TMDCs, phosphorene, and graphene, respectively.…”

Tuneable strong optical absorption in a graphene-insulator-metal hybrid plasmonic device

“…An ionic gel layer is further placed on top of graphene in order to provide a highly efficient gating method for achieving strong electrostatic doping of the atomic monolayer (there is a large variety of ionic gel types that can be used 28 ). Using an ionic gel as the top dielectric overcoat material in a gate setup 28 , 29 enables strong modulation of the chemical potential at low voltage operation (from 0 eV up to 0.8 eV within 3 V of applied voltage) 30 thus providing a wide wavelength tuning range for plasmon excitations in the graphene layer. The inclusion of the spacer and ion gel layers also results in the formation of a weak 1-dimensional micro-cavity transverse to the grating surface that is also known as a Salisbury screen 13 .…”