A Silver Solution

Abstract

CHEMISTRY Despite widespread efforts toward development of printable semiconductors for large-area, flexible electronics media, far less attention has been given to the printable conducting material required for the wiring and connections within such devices. Both gold and silver possess high conductivity and operational stability, but precise patterning with these metals typically requires vacuum deposition. Wu et al. have devised a simple solution-based process for patterning conductive silver features on a substrate. Using coating, stamping, or printing techniques, they deposit an alcohol solution containing a silver(I) salt, a hydroxyalkylamine, and a long-chain carboxylic acid. Subsequent heating at relatively low temperature (150°C) forms the conducting silver elements. The amine functions as a gentle reducing agent, with sufficient volatility to evaporate easily afterward. Achieving high conductivity requires acid additives with decyl or longer alkyl tails, which foster the growth of films without discernible grain boundaries. The method was applied to fabrication of a layered thin-film transistor device, in which the silver showed conductivity comparable to that of more costly vacuum-processed gold. — MSL J. Am. Chem. Soc. 129 , 10.1021/ja067596w (2007).