Micro-networked metal coating using self-cracked WO3 inorganic thin film as sacrificial layer: Application to transparent flexible electrodes

Highlights: • Micro-networked metal electrode using a self-cracked WO3 film as a sacrificial layer. • Electrical conductivity of approximately ∼100 Ω/sq was measured. • An average transmittance was 95.6% in the visible light region. • The electrical resistance was maintained stable with repeated bending tests (>10000). A method of fabricating a micro-networked metal electrode using a self-cracking WO₃ oxide thin film as a sacrificial layer is presented. The width of the formed crack can be adjusted to a size of 10 to 40 µm by adjusting the wet-etching time in dilute NaOH solution, and accordingly, the electrical conductivity and transmittance of the electrode can be adjusted. An electrical conductivity of approximately 100 Ω/sq was measured at an average transmittance of 95.6% in the visible light region, and when applied to a flexible substrate, the electrical resistance was maintained stable even with repeated bending tests. The method proposed in this study can be applied to various transparent flexible electrode devices.