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Hai-Bo Chena) Key Laboratories of Bioorganic Chemistry and Molecular Engineering of Ministry of Education, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China

Jian Wangb) Institute of Polymer Optoelectronic Materials and Devices, South China University of Technology, Key Laboratories of Specially Functional Materials, Ministry of Education, Guangzhou 510640, China

Jian Peic) Key Laboratories of Bioorganic Chemistry and Molecular Engineering of Ministry of Education, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China (Received 12 April 2010; accepted 3 December 2010)

An ecofriendly process has been successfully developed to synthesize the polycrystalline silver nanopolyhedrons with a high yield at large scale. By using tannic acid in the presence of poly (vinyl pyrrolidone) (PVP), high quality silver nanopolyhedrons were obtained in an aqueous one-pot reaction without any templates or auxiliaries. The film made from the silver nanostructures exhibits an electrical conductivity higher than 104 S/cm on both rigid and flexible substrates. The supreme mechanical strength of this silver film recommends its wide application in printing and flexible electronics.

With the rapid growth of printed electronics and flexible devices, conducting fluids or conductive inks become a prerequisite for large area and ultra-low-cost electronics.1–3 The conducting elements in the inks are usually noble metal micropolyhedrons or nanopolyhedrons, such as gold and silver.4–6 However, the high cost of gold impedes the development of application of gold-based conductive inks in low-cost electronics. Therefore, silver nanoparticle-based conductive inks become attractive in terms of cost, as well as electrical and thermal conductivity.3,7 In addition, the applications of silver conductive materials in flexible electronics ask for low temperature processable inks that can be converted into metallic films with high electrical conductivity (.104 S/cm) by thermal treatment at a relatively low temperature (~150 °C). Using a solution process to fabricate silver nanopolyhedrons is preferred to other methods, such as electrochemical deposition,8 photochemical synthesis,9 and microwave-assisted preparation,10 due to the solution process’s low cost, large-scale operation, and easilycontrolled process parameters. However, most solution processing methods use organic solvents and nona) These authors contributed equally to this work. Address all correspondence to these authors: b) e-mail: [email protected] c) e-mail: [email protected] DOI: 10.1557/jmr.2010.95

J. Mater. Res., Vol. 26, No. 4, Feb 28, 2011

http://journals.cambridge.org

Downloaded: 18 Mar 2015

ecofriendly reducing agents and auxiliaries.11,12 Herein, we report a silver nanopolyhedron-based conductive ink that shows high electrical conductivity with low annealing temperature through a green chemistry type procedure. In our synthesis strategy, we chose silver nitrite as the metal source, a nontoxic compound polyvinylpy