Roll-to-roll redox-welding and embedding for silver nanowire network electrodes

Area of Science:

• Materials Science
• Nanotechnology
• Optoelectronics

Background:

• Transparent conductive films are crucial for flexible electronics.
• Traditional materials like Indium Tin Oxide (ITO) are brittle and expensive.
• Silver nanowire (AgNW) networks offer a promising alternative but require improved fabrication methods.

Purpose of the Study:

• To develop a continuous, scalable method for fabricating high-performance AgNW electrodes.
• To enhance the electrical conductivity, mechanical robustness, and optical properties of AgNW films.
• To demonstrate the application of these electrodes in flexible organic light-emitting diodes (OLEDs).

Main Methods:

• A continuous roll-to-roll redox-welding process involving sequential oxidation (HNO3) and reduction (NaBH4) in aqueous solution.
• Oxidation generates Ag+ ions for autocatalytic redeposition, fusing nanowire junctions.
• Reduction removes oxide layers, improving conductivity.
• Roll-to-roll embedding of AgNWs in UV curable resin for electrode fabrication.

Main Results:

• Achieved a sheet resistance of 11.3 Ω sq⁻¹ with 90.5% optical transmittance at 550 nm.
• Significantly improved mechanical robustness of AgNW electrodes compared to as-coated films.
• Fabricated large-area flexible OLEDs using redox-welded AgNWs as anode electrodes.
• OLED devices showed superior performance to those with as-coated AgNWs and were comparable to ITO-based devices.

Conclusions:

• The developed roll-to-roll redox-welding and embedding method is a facile and reliable approach for large-area transparent flexible electrode fabrication.
• This method offers a viable pathway for next-generation flexible optoelectronic devices.
• Redox-welding significantly enhances the performance and durability of AgNW electrodes.