Morphological Regulation of Printed Low-Temperature Conductive Ink

The unbalanced evaporation of solvents in lowtemperature sintered inks for printed electronics leads to a series of problems in the actual printing process, including printed pattern distortion, surface cracking, and the coffee ring effect, which has become a serious obstacle to this technique. Here, we present a comprehensive investigation of the influence of the solvent composition, environmental, and sintering conditions on the complicated pattern formation process of reactive silver inks. The results first showed that only inks with a certain wettability of solvents could form well-defined patterns. Then, the solvent composition and ambient humidity can be adjusted to balance the nonequilibrium evaporative flow within the liquid and thus to obtain a flat liquid film. Combined with the rapid UV sintering process, the particle size, porosity, and roughness could be controlled to produce dense and homogeneous silver films. Finally, we successfully printed silver electrodes with a smooth and dense surface (Rqs similar to 21 nm in 0.8 x 0.8 mm2 area and less than 1% porosity) under an optimized relative humidity (RH) of 50-60% at room temperature with the solvent composition of IPA (isopropanol)/2,3-BD (2,3-butanediol) = 8:2. In addition, we also demonstrated high-performance Pr-IZO (praseodymium-doped indium-zinc oxide) thin film transistors (TFTs) with a mobility (mu sat) of 2.14 cm2/V/s and Ion/Ioff ratio of over 107 using source-drain electrodes printed under optimized conditions. [GRAPHICS] .

Automated summary

This study comprehensively investigates the influence of solvent composition, environmental humidity, and sintering conditions on the formation process of complex patterns in reactive silver inks. The results show that only inks with a certain solvent wettability can form well-defined patterns. By adjusting the solvent composition and ambient humidity, the non-equilibrium evaporative flow within the liquid can be balanced, resulting in a flat liquid film. Furthermore, the particle size, porosity, and roughness of the silver films can be controlled through rapid UV sintering, producing dense and homogeneous films.