Spontaneous post-growth oxygen dissipation and electrical improvement of silver electrodes in substoichiometric oxidation states

• Published in: Applied surface science 2023-06, Vol.623, p.156998, Article 156998
• Main Authors: Jeong, Eunwook, Lee, Sang-Geul, Yu, Seung Min, Han, Seung Zeon, Lee, Gun-Hwan, Ikoma, Yoshifumi, Choi, Eun-Ae, Yun, Jungheum
• Format: Article
• Language: English
• Subjects: Density functional theory calculations; Oxide reduction; Silver; Substoichiometric oxidation; Thin film electrode
• ISSN: 0169-4332; 1873-5584
• DOI: 10.1016/j.apsusc.2023.156998

This study presents experimental and computational evidence of the spontaneous post-growth dissipation of oxygen from Ag lattices in extremely oxygen-deficient substoichiometric oxidation states. [Display omitted] •Solid evidence supports spontaneous post-growth reduction of substoichiometric Ag.•Extremely O-deficient suboxidation states improve Ag wetting on oxides.•Thermodynamic formation energy induces O out-diffusion to Ag surfaces.•O segregation and spillover from Ag surfaces induces null residence of O in Ag layers.•Intensified O dissipation improves optoelectrical performance of Ag layers. Thermodynamically stable stoichiometric and higher oxidation states are known to be detrimental to the electrical and optical performances of Ag electrodes. In contrast, thermodynamically less stable or unstable suboxidation states entailing extreme O deficiencies are scarcely understood because the tenuous or null trace of O in suboxidized Ag domains is difficult to detect. This paper presents an experimental confirmation and numerical interpretation of the extreme suboxidation of Ag-layered electrodes and the influences of the post-growth reduction on their optoelectrical properties. A significant decrease in the electrical resistance of such suboxidized Ag layers is observed during post-growth storage under an ambient atmosphere with 40% relative humidity at 290 K, which is instantly implemented by covering the Ag layers with an atomically thin ZnO overlayer. The results indicate that the electrical improvement is attributed to the spontaneous post-growth reduction of Ag suboxides, which is driven by two sequential post-growth dynamics, namely, the strong segregation of atomic O originally incorporated in Ag suboxides to the outermost surface and the spillover of O to either the ambient atmosphere or ZnO overlayer. These findings provide a solution for implementing the optoelectrical and structural advantages of Ag electrodes by employing suboxidation without aftereffects.