Preparation of highly conductive gold patterns on polyimide via shaking-assisted layer-by-layer deposition of gold nanoparticles

Shaking-assisted LBL deposition of gold nanoparticles (GNPs, 2.5 ± 0.5 nm) was carried out, along with the use of small non-toxic ethylenediamine (EDA) linker molecules for easy removal by sintering, in order to produce highly conductive gold patterns on polyimide substrates. First, shaking time were optimized by measuring the surface coverage of the first layer using large GNPs (12.8 ± 1.4 nm) since 2.5 nm GNPs are too small to be analyzed by FE-SEM. The concentration of EDA linker molecules and dipping time were also optimized by measuring the UV–vis absorption. Next, multilayer formation was demonstrated by measuring the NIR transmittance, multilayer thickness, and electrical conductivity, and compared with multilayer films prepared by conventional LBL deposition. Finally, gold patterns were prepared by patterning 20-layer film of small GNPs (line width of 10 μm) and subsequent sintering at 150 °C for 1 h. The shaking-assisted LBL deposition of GNPs produced clean gold patterns with very high electrical conductivity (2 × 105 Ω−1 cm−1) and short deposition time (∼10 min) per layer.