Voltage Control of Patterned Metal/Insulator Properties in Oxide/Oxyfluoride Lateral Perovskite Heterostructures via Ion Gel Gating

Abstract

Dynamic control of patterned properties in perovskite oxide films can enable new architectures for electronic, magnetic, and optical devices. In this study, it is shown that SrFeO3‐δ/SrFeO2F laterally‐heterostructured films enable voltage‐controlled tunable and reversible metal‐insulator patterned properties using room‐temperature ion gel gating. Specifically, SrFeO3‐δ film regions can be toggled between insulating HxSrFeO2.5 and metallic SrFeO3 by electrochemical redox, while SrFeO2F regions remain robustly insulating and are unaffected by ion gel gating. Various gating architectures are also compared and establish the advantages of employing a conductive substrate as the contacting electrode, as opposed to at the film surface, thereby achieving complete and reversible reduction and oxidation among SrFeO3‐δ, HxSrFeO2.5, and SrFeO3. This approach to voltage‐modulated patterned electronic, optical, and magnetic properties should be broadly applicable to oxide materials amenable to fluoridation, and potentially other forms of anion substitution.

Mechanisms of Hysteresis and Reversibility across the Voltage-Driven Perovskite–Brownmillerite Transformation in Electrolyte-Gated Ultrathin La0.5Sr0.5CoO3−δ

“…It is now understood that this can be achieved via ionic liquids and gels, − solid electrolytes, ,− and ionic conductors, ,− utilizing these media to control the insertion/extraction of various chemical species into/out of target materials they are interfaced with. These species include oxygen ions/vacancies (O/V O ), − H ions, ,− ,,,,,,, Li ions, ,, N ions, , F ions, etc., inserted/extracted into/from a variety of target materials, spanning metals, − ,,,, oxides, − ,− ...…”

“…It is now understood that this can be achieved via ionic liquids and gels, 1−5 solid electrolytes, 2,5−7 and ionic conductors, 2,5−7 utilizing these media to control the insertion/extraction of various chemical species into/out of target materials they are interfaced with. These species include oxygen ions/vacancies (O/V O ), 2−33 H ions, 2,[5][6][7]13,25,28,30,31,34,35 Li ions, 28,36,37 N ions, 38,39 F ions, 40 etc., inserted/extracted into/from a variety of target materials, spanning metals, [5][6][7]9,10,35,37 oxides, [2][3][4][5][6][7][8]40 two-dimensional materials, [3][4][5]28,36 nitrides, 38,39 polymer semiconductors, 1,3 and more. Devices operating on these principles are electrochemical transistors, where a gate voltage (V g ) across the electrolyte or ionic conductor controls the properties of the target material electrode through ion insertion/extraction, merging concepts from materials science, electrochemistry, physics, and electrical engineering.…”

Ionogels: recent advances in design, material properties and emerging biomedical applications

“…Since the first reports of IL-based gels with either organic or inorganic host networks in 2005, 8,9 much effort has been dedicated to the research on IL-based gels, which have been applied in many fields, such as energy storage, bioelectronics, sensors, and actuators. [10][11][12][13][14] Among these reported works, several naming systems have been found, such as ionic liquid gels, 15 ionogels, 16 ion gels, 17,18 ion-gels 19 and iongels, 20 which make it difficult to reference. In this review, we will adapt ionogels as the name.…”

Optical Properties of Electrochemically Gated La1−xSrxCoO3−δ as a Topotactic Phase‐Change Material

“…[34][35][36] As a result, electrolyte gating has enabled dramatic voltage-driven modulation of electronic, magnetic, and optical properties, in systems such as 2D materials, [37,38] organic semiconductors, [39,40] and oxides. [25,[34][35][36][41][42][43][44][45] Critically, it is now understood that the operation of such devices can be electrostatic (via induction of electrons/holes), or electrochemical, but both can be reversible. [34,35] In oxides, for example, the interfacial electric field can remove or insert oxygen ions (depending on the V g polarity), generating a nonvolatile but reversible redox-based voltage response.…”