Silver Nanofilament Formation Dynamics in a Polymer-Ionic Liquid Thin Film by Direct-Write

Area of Science:

• Materials Science
• Electrochemistry
• Nanotechnology

Background:

• Solid polymer electrolytes are crucial for advanced electronic devices.
• Ionic liquids offer unique properties for electrochemical applications.
• Controlling nanoscale material formation is key for device performance.

Purpose of the Study:

• To investigate the dynamics of silver nanofilament formation in ionic liquid-filled polymer electrolytes.
• To understand the influence of applied bias on filament growth and morphology.
• To explore the relationship between electric double layer formation and nanofilament kinetics.

Main Methods:

• Direct-write process using conductive atomic force microscopy (C-AFM).
• Electrochemical formation of silver nanofilaments on polyethylene glycol diacrylate (PEGDA)/[BMIM]PF6 electrolyte.
• Scanning electron microscopy (SEM) for morphological analysis.
• Time-dependent current measurements to analyze growth dynamics.

Main Results:

• Silver nanofilaments were formed at multiple locations on a ~40 nm thick polymer electrolyte.
• Filament formation time generally decreased with increasing bias (0.7-3.0 V), with an unexpected maximum at ~2.0 V.
• The observed 'inverted kinetics' at ~2.0 V were attributed to electric field screening by ionic liquid electric double layers (EDLs).
• Nanofilaments formed in the inverted region exhibited more lateral and diffuse features.
• Two distinct nanofilament growth dynamics were identified: abrupt (ms) and gradual (hundreds of ms), dependent on EDL screening.

Conclusions:

• The study reveals a non-monotonic relationship between applied bias and silver nanofilament formation time.
• Electric double layer screening in ionic liquids significantly influences nanofilament growth kinetics and morphology.
• Tuning formation time and dynamics by controlling IL behavior enables accessible resistance states for neuromorphic applications.