Inkjet printing of silver nanowire electrodes for fully stretchable organic light-emitting diodes

Abstract

Stretchable organic light-emitting diodes (OLEDs) are essential for display and interaction in wearable electronics. However, inkjet-printed silver nanowire (AgNW) films for OLED electrodes are limited by poor film uniformity, high surface roughness, and insufficient stretchability. Here, an integrated strategy is proposed to address these challenges through cosolvent modulation, substrate transfer, and junction soldering. Specifically, a high-viscosity cosolvent (1-pentanol) was introduced into the AgNW ink to suppress the outward capillary flow during drying. This effectively mitigated the coffee ring effect and significantly improved film uniformity. On this basis, the AgNW films were embedded into a thermoplastic polyurethane/polydimethylsiloxane (TPU/PDMS) elastomeric matrix via a substrate transfer process, utilizing the water solubility of the initial PEDOT:PSS substrate. This process reduced the root-mean-square surface roughness from 23.9 nm to 4.1 nm and the maximum peak-to-valley roughness from 188.2 nm to 29.9 nm. Furthermore, the inter-nanowire junctions were soldered using a small-molecule additive (4′-pentyl-4-cyanobiphenyl, 5CB) to further enhance mechanical stability. This reduced the relative resistance change (R/R₀) under 100% strain from 99 to 12. Based on the optimized electrodes, the fully inkjet-printed stretchable OLED devices were successfully fabricated. The devices exhibited a maximum luminance of 3141 cd m⁻², corresponding to 84% of that of the spin-coated reference device. Under 100% strain, the devices retained 38% of the initial luminance. These results demonstrate a viable and scalable route toward high-performance, fully printed stretchable OLEDs.