Hierarchically-structured silver nanoflowers for highly conductive metallic inks with dramatically reduced filler concentration

Silver has long been employed as an electrically conductive component, and morphology-dependent properties have been actively investigated. Here we present a novel scalable synthesis method of flower-shaped silver nanoparticles (silver nanoflowers, Ag NFs). The preferential affinity of citrate molecules on (111) surface of silver enabled spontaneous anisotropic growth of Ag NFs (bud size: 250 similar to 580 nm, single crystalline petal thickness: 9 similar to 22 nm) with high reproducibility and a high yield of > 99.5%. The unique hierarchical structure resulted in coalescence of petals over 80 similar to 120 degrees C which was practically employed in conductive inks to construct percolation pathways among Ag NFs. The ink with only 3 wt% of Ag NFs provided two orders of magnitude greater conductivity (1.008 x 10(5) Scm(-1)), at a low curing temperature of 120 degrees C, compared with the silver nanoparticle ink with a much higher silver concentration (50 wt%). This extraordinary property may provide an excellent opportunity for Ag NFs for practical applications in printable and flexible electronics.