Excimer laser sintereing of silver nanoparticles electrodes for fully solution processed organic thin film transistors

Printing and related processing technologies of electronic materials have become an essential part in the production of many components of today's electronics. Laser processing of metal based inks in particular has received a great attention and can eliminate the need of the conventional high temperature sintering methods. Here, silver nanoparticles ink was printed using a drop on demand (DOD) printer and cured to produce highly conductive silver patterns. The printed silver nanoparticles were sintered using excimer laser and thermal treatment. The effects of curing parameters such as energy density, scan speed and annealing temperature on the surface morphology and electrical performance of the inkjet printed structures were investigated. The results revealed strong dependence of the morphology and electrical performance of the printed samples on the process parameters namely the laser fluence and the scanning speed. The production of discontinuous samples and laser ablation of silver sintered patterns at some treatment stages were also noticed. Moreover, using optimized sintering conditions, highly conductive patterns similar to those thermally treated were produced. The printed conductive patterns were then successfully utilized as S/D electrodes for organic thin film transistors. The fully solution processed transistors with printed silver electrodes exhibited excellent ohmic contact characteristics with mobility and on/off ratio in the range of 10(-2) cm(2)/V.s and 10(3), respectively. The results indicate that, in addition to the various material processing uses, excimer laser can also be used as a sintering tool for printed metallic nanoparticles in the roll-to-roll manufacturing processes.