LOW TEMPERATURE SOLUTION PROCESS FOR FABRICATION OF ELECTRODES ON FLEXIBLE SUBSTRATE USING GOLD NANOPARTICLES

Abstract

Inkjet printing technology has emerged as major contender for large area electronics. The major challenge for this technology is the development of suitable conductive ink to obtain high quality patterns with desired electrical conductivity comparable to metals. The conductive ink should have good film formability on the flexible substrate as well as lower annealing temperature compatible with plastic substrates. Gold nano particle (AuNP) is the material of choice due to its very low sintering temperature in addition to excellent electrical property and resistance to corrosion. We have synthesized the butanethiol encapsulated Au-NP by the Brust method. We demonstrate a sintering temperature as low as 150°C for butanethiol capped gold nanoparticles of size less than 2 nm. The conductive gold films obtained after transformation have been investigated using four point probe method to measure sheet resistance as a function of process time. We show that the electrical properties degrade as annealing time increases. The reason for changes in electrical property has been investigated using SEM, TEM and XRD. The decrease in conductivity is traced to the formation of large micron sized gold crystallites on the film surface at temperatures as low as 160°C.