Molecular Conversion of Thermally Stable Cu-Ag Networks for Mechanically Robust Printed Electronics

Copper-silver inks are promising for printed electronics owing to their high electrical conductivity and oxidation resistance, yet their practical use is limited by silver migration under thermal bias, structural aggregation during curing and sintering, and insufficient mechanical reliability. Here, we report a particle-free metal-organic reactive ink enabled by an in situ sequential reduction strategy, in which copper is first generated via self-reduction and subsequently coated with a conformal Ag shell through in situ electroless deposition. This process forms a percolative Ag-surface-enriched Cu conductive network without the use of preformed nanoparticles. By eliminating discrete particle precursors, the optimized conductor develops a dense, highly interconnected morphology and achieves a high electrical conductivity of 4.3 MS m^{- 1}. The printed conductors retain stable electrical performance at temperatures up to 800°C and withstand thermal aging in ambient air at 700°C for 48 h. Structural analyses reveal that the conformal Ag shell preserves network continuity and suppresses high-temperature degradation. This particle-free strategy avoids the aggregation inherent to conventional particle-based inks, offering a scalable route to printed conductors with enhanced high-temperature electrical and mechanical reliability.