Ring Stain Effect at Room Temperature in Silver Nanoparticles Yields High Electrical Conductivity

• Published in: Langmuir 2005-11, Vol.21 (23), p.10264-10267
• Main Authors: Magdassi, Shlomo, Grouchko, Michael, Toker, Dana, Kamyshny, Alexander, Balberg, Isaac, Millo, Oded
• Format: Article
• Language: English
• Subjects: Chemistry; Colloidal state and disperse state; Exact sciences and technology; General and physical chemistry; Physical and chemical studies. Granulometry. Electrokinetic phenomena
• ISSN: 0743-7463; 1520-5827
• DOI: 10.1021/la0509044

We demonstrate that metallic rings formed spontaneously at room temperature via evaporation of aqueous drops containing silver nanoparticles (20−30 nm in diameter) exhibit high electrical conductivity (up to 15% of that for bulk silver). The mechanism underlying this self-assembly phenomena is the “ring stain effect”, where self-pinning is combined with capillary flow to form a ring consisting of close-packed metallic nanoparticles along the perimeter of a drying droplet. Our macroscopic and microscopic (applying conductive atomic force microscopy) transport measurements show that the conductivity of the ring, which has a metallic brightness, is orders of magnitude larger than that of corresponding aggregates developed without the ring formation, where high conductivity is known to appear only after annealing at high temperature.