Maskless soft lithography for fabricating micro- and nano-scale Ag structures via solid-state electrochemical etching using a polymer electrolyte membrane for optoelectronic and sensing applications

Abstract

Micro/nanostructured Ag surfaces are promising candidates for transparent electroconductive films and highly sensitive plasmonic sensors. However, the conventional patterning procedures are complex and expensive. Here, a direct and simple patterning method is developed via solid-state electrolysis using a polymer electrolyte membrane (PEM) stamp. Anodic dissolution of the Ag surface occurs at the PEM/material interface. The Ag ions are transferred through the PEM and deposited as a thin Ag film at the cathode. By optimizing the process conditions, a high etching rate of ∼6 μm min⁻¹ can be achieved to produce well-defined patterns with resolutions ranging from micrometers to hundreds of nanometers. Multiple processing steps can be combined to generate complex hierarchical structures. This process is performed at room temperature without harsh chemicals and capable of creating Ag patterns on flexible polymer substrates. The resulting patterned surfaces exhibit enhanced optical transmittance, supporting their potential use as flexible electroconductive transparent membranes. The patterned Ag surfaces also enable highly sensitive detection of rhodamine, demonstrating their suitability for surface-enhanced Raman spectroscopy. This fast and facile solid-state electrochemical etching has reduced the environmental impact and cost, making it advantageous for fabricating optoelectronic devices and bio/chemical sensor templates.