N-heterocyclic carbene-silver complexes: Potential conductive materials for silver pastes in electronic applications

摘要

New organosilver complexes, silver(I) tetraalkylbis(benzimidazolidene) halide [1a-3a] and silver(I) dimethyl-N,N′-hexyl(imidazolyl) bromide [4a], were synthesized and incorporated into electroconductive silver pastes. Complex 3a had a 15-fold higher conductivity than conventional silver salt pastes, specifically silver(I) hexanoate, and exhibited a smooth, homogeneous surface after reductive heat-treatment of the silver paste. While the conductivity of silver(I) hexanoate can be increased by up to 33% by the addition of a supporting silver source, such as Ag2O, the conductivity of 3a was markedly decreased by Ag2O treatment. Thus, 3a can be used in silver pastes with moderate conductivity and can reduce the amount of conventional silver supporting materials without loss of electroconductivity.