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High Metal-Insulator Topotactic Cycling Endurance in Electrochemically Gated La0.5Sr0.5CoO3-δ Probed by
Rohan D Chakraborty1, Jierui Liang1, Nileena Nandakumaran1
1Department of Chemical Engineering and Materials Science, University of Minnesota, 421 Washington Avenue SE, Minneapolis, Minnesota 55455, United States.
ACS Nano
|May 2, 2025
Summary
Improving cycling endurance in La0.5Sr0.5CoO3-δ (LSCO) films is key for tunable infrared photonic devices. This study optimizes humidity and contacts for stable metal-insulator transitions in LSCO, achieving record endurance.
Area of Science:
- Materials Science
- Condensed Matter Physics
- Electrochemistry
Background:
- Electrochemical gating of La0.5Sr0.5CoO3-δ (LSCO) films induces significant optical changes via a metal-insulator transition.
- The perovskite to brownmillerite phase transformation in LSCO limits cycling endurance, with the role of water unclear.
Purpose of the Study:
- To explore extended cycling endurance in ion-gel-gated LSCO electrochemical transistors.
- To investigate the influence of relative humidity on the electrochemical cycling and optical properties of LSCO.
- To establish guiding principles for enhancing cycling endurance in electrochemically tunable functional oxides.
Main Methods:
- Operando FTIR transmittance measurements were used to monitor optical changes during electrochemical cycling.
- LSCO electrochemical transistors were cycled under varying relative humidity conditions.
- Device contacts (Pt vs. Au) and environmental humidity were systematically varied.
Main Results:
- Higher humidity accelerates oxygen reinsertion but causes LSCO etching and contact degradation, limiting endurance.
- Optimized conditions (15% relative humidity, Au contacts) enabled over 40 cycles with sustained optical modulation up to 100 cycles.
- A new record for metal-insulator optical property endurance was set for electrochemically gated perovskite oxides.
Conclusions:
- Humidity control and appropriate contact materials are critical for achieving long-term stability in electrochemically gated LSCO devices.
- The findings support the use of ion-gel-gated LSCO for tunable infrared photonic applications.
- This work provides essential insights for improving the cycling stability of other electrochemically responsive materials.
