Application of flash-light sintering method to flexible inkjet printing using anti-oxidant copper nanoparticles

Copper nanoparticles were protected against oxidation by coating with 1-octanethiol. The copper nano-ink was synthesized by dispersing the coated copper powder in 1-octanol solvent at a concentration of 18 wt%. Inkjet patterns printed on a flexible polyimide film and subjected to flash-light sintering displayed excellent anti-oxidation behavior over 2 months. The optimal light-sintering condition was 24.7 J/cm2 of energy density from a 5-ms pulse, which resulted in a resistivity of 2.4 × 10−7 Ω∙m. After bending more than 1000 times, the resistivity of the light-sintered pattern was 1.45-times higher than that of the unbent pattern. The light-sintered pattern printed with the anti-oxidative copper nano-ink shows great promise for flexible device applications.