Pulse Dynamics of Electric Double Layer Formation on All-Solid-State Graphene Field-Effect Transistors

Area of Science:

• Materials Science
• Condensed Matter Physics
• Electrochemistry

Background:

• Electric double-layer (EDL) formation is critical for the operation of graphene field-effect transistors (FETs) and emerging EDL transistors (EDLTs).
• Understanding the dynamics of EDL formation in polymer electrolytes is essential for optimizing device performance and speed.

Purpose of the Study:

• To investigate the dynamics of electric double-layer formation in graphene FETs using polyethylene oxide (PEO)-based electrolytes.
• To compare experimental observations with molecular dynamics (MD) simulations across different timescales.
• To determine the influence of electric field strength on EDL formation rates and carrier densities.

Main Methods:

• Experimental study of EDL formation in graphene FETs with PEO:CsClO4 electrolytes using timescales from microseconds to milliseconds.
• Molecular dynamics (MD) simulations of EDL formation in PEO:LiClO4 electrolytes between graphene electrodes, probing picosecond to nanosecond timescales.
• Varying applied electric field strengths in both experimental and simulation approaches.

Main Results:

• Experimentally, EDL formation in graphene FETs with PEO:CsClO4 occurs on microsecond timescales and strengthens to sheet carrier densities of ~10^13 cm^-2 within 1 ms.
• MD simulations show EDL formation initiating in sub-nanoseconds at high electric fields (100 mV/nm), reaching charge densities up to 6 × 10^13 cm^-2 within 3 ns.
• The study demonstrates that EDL formation timescales can be tuned over nine orders of magnitude by adjusting the electric field strength over three orders of magnitude.

Conclusions:

• EDL formation in graphene FETs with PEO electrolytes is a dynamic process tunable by electric field strength.
• High electric fields enable rapid EDL formation on nanosecond timescales, relevant for high-speed electronic applications like EDLTs.
• The combined experimental and simulation approach provides a comprehensive understanding of EDL dynamics across a vast range of timescales.