Mechanism of photo-ionic stoichiometry changes in SrTiO3

Viernstein, Alexander; Kubicek, Markus; Morgenbesser, Maximilian; Huber, Tobias M.; Ellmeyer, Emil; Siebenhofer, Matthäus; Vaz, C. A. F.; Fleig, Jürgen

doi:10.1016/j.ssi.2022.115992

Cited by 4 publications

(1 citation statement)

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“…The oxygen chemical potential (or quasi chemical potential) may vary in a complex way with respect to depth. 13,14 Therefore, in the present work we study thin films where a) film thickness is on the order of the absorption length, and b) kinetics are expected to be limited by oxygen surface exchange at the solid−gas interface rather than by diffusion (at least in the dark), if in fact oxygen is transferred.…”

Section: Introductionmentioning

confidence: 99%

UV-Driven Oxygen Surface Exchange and Stoichiometry Changes in a Thin-Film, Nondilute Mixed Ionic Electronic Conductor, Sr(Ti,Fe)O_3-d

Skiba,

Buckner,

Lee

et al. 2024

J. Am. Chem. Soc.

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Enabling light-controlled ionic devices requires insight into photoionic responses in technologically relevant materials. Mixed-conducting perovskites containing nondilute Feserving as electrodes, catalysts, and sensorscan support large, electronically accommodated excursions in oxygen content, typically controlled by temperature, bias, and gas atmosphere. Instead, we investigated the ability of low-fluence, above-bandgap illumination to adjust oxygen stoichiometry and drive oxygen fluxes in nondilute Sr(Ti1–x Fe x )O3–x/2+δ (x = 0.07, 0.35) thin films with high baseline hole concentrations. Films’ optical transmission at 2.8 eV was used as a probe of oxygen stoichiometry in the range ∼100–500 °C. We compared pO2-step-driven and UV (3.4 eV)-step-driven visible optical transmission relaxations in films, finding that the time constants and activation energies of the relaxations were consistent with each other and thus with oxygen-surface-exchange-limited kinetics. Blocking oxygen exchange at the solid–gas interface with a UV-transparent capping layer resulted in no UV-induced optical relaxations. These results demonstrate that above-bandgap illumination can increase oxygen content in nondilute compositions through oxygen flux into the solid from the gas. First-principles simulations of defect formation enthalpies indicate that oxygen vacancies are energetically less favorable under steady-state illumination owing to shifts in quasi-Fermi levels. A larger 2.8 eV-optical response to UV illumination in x = 0.07 vs x = 0.35 samples was further investigated through ultrafast transient spectroscopy, where it was found that the x = 0.07 sample exhibits a slower carrier recombination. Together, these results suggest potential design principles for materials supporting large stoichiometry changes under above-gap illumination: (1) long excited carrier lifetimes and (2) highly charged, rather than neutral, defects/associates.

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Section: Introductionmentioning

confidence: 99%

UV-Driven Oxygen Surface Exchange and Stoichiometry Changes in a Thin-Film, Nondilute Mixed Ionic Electronic Conductor, Sr(Ti,Fe)O_3-d

Skiba,

Buckner,

Lee

et al. 2024

J. Am. Chem. Soc.

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Fabrication of Ti3C2/TiO2/SrTiO3 ternary heterojunction photocatalyst with efficient charge separation for enhanced hydrogen evolution

Ye,

Zhong,

Zhang

et al. 2024

International Journal of Hydrogen Energy

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Application of impedance spectroscopy to analyze the electrical properties of cobalt doped SrTiO3

Siqueira

Campos

2023

Solid State Ionics

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Mechanism of photo-ionic stoichiometry changes in SrTiO3

Cited by 4 publications

References 46 publications

UV-Driven Oxygen Surface Exchange and Stoichiometry Changes in a Thin-Film, Nondilute Mixed Ionic Electronic Conductor, Sr(Ti,Fe)O_3-d

UV-Driven Oxygen Surface Exchange and Stoichiometry Changes in a Thin-Film, Nondilute Mixed Ionic Electronic Conductor, Sr(Ti,Fe)O_3-d

Fabrication of Ti3C2/TiO2/SrTiO3 ternary heterojunction photocatalyst with efficient charge separation for enhanced hydrogen evolution

Application of impedance spectroscopy to analyze the electrical properties of cobalt doped SrTiO3

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Mechanism of photo-ionic stoichiometry changes in SrTiO3

Cited by 4 publications

References 46 publications

UV-Driven Oxygen Surface Exchange and Stoichiometry Changes in a Thin-Film, Nondilute Mixed Ionic Electronic Conductor, Sr(Ti,Fe)O3-d

UV-Driven Oxygen Surface Exchange and Stoichiometry Changes in a Thin-Film, Nondilute Mixed Ionic Electronic Conductor, Sr(Ti,Fe)O3-d

Fabrication of Ti3C2/TiO2/SrTiO3 ternary heterojunction photocatalyst with efficient charge separation for enhanced hydrogen evolution

Application of impedance spectroscopy to analyze the electrical properties of cobalt doped SrTiO3

Contact Info

Product

Resources

About

UV-Driven Oxygen Surface Exchange and Stoichiometry Changes in a Thin-Film, Nondilute Mixed Ionic Electronic Conductor, Sr(Ti,Fe)O_3-d

UV-Driven Oxygen Surface Exchange and Stoichiometry Changes in a Thin-Film, Nondilute Mixed Ionic Electronic Conductor, Sr(Ti,Fe)O_3-d