Flash Light Sintering of Silver Nanoink for Inkjet-Printed Thin-Film Transistor on Flexible Substrate

In this paper, we study flash light sintering of inkjet-printed silver nanoink and show its application in printed and flexible thin film transistors. Flash method, which uses pulsed light to sinter metal nanoparticles, is a very fast and low-temperature sintering method. Hence, it facilitates in quick fabrication of low cost, flexible electronic devices. In the current work, various silver patterns were obtained by inkjet printing of silver nanoink on flexible substrate and then the patterns were sintered by flash method. Several flash sintering parameters were carefully optimized to achieve high electrical conductivity. In next stage, such printed and flash sintered silver patterns were used as source and drain contacts in thin-film transistor. Indium tin oxide coated polyethylene terephthalate sheet was used as substrate as well as bottom gate contact in transistor structure. On the other hand, polystyrene and pentacene were used in gate dielectric and channel layer, respectively. Such printed transistor with channel length of 28 μm and width of 68 μm exhibited field effect mobility of 0.09 cm
²
V
^-1
s
^-1
and ON/OFF ratio on the order of 10
⁶
. Finally, a comparative study was made between transistor performance with printed silver contacts and vacuum deposited silver contacts to ensure printing and sintering steps do not cause any notable degradation to the organic semiconducting layer.