Fabrication of flexible electronics by laser-aided processing of nanoparticles

Abstract

A new paradigm will be presented for the low temperature fabrication of passive (conductor, capacitor) and active (field effect transistor) electrical components on the flexible polymer substrate. A drop-on-demand (DOD) ink-jetting system was used to print gold nano-particles suspended in carrier solvents, insulating polymer material and a semiconductor polymer to fabricate passive and active electrical components on flexible polymer substrates. Low power, short-pulsed laser ablative material removal enabled finer electrical components to overcome the resolution limitation of inkjet deposition. Temporally modulated laser irradiation was utilized to locally evaporate the carrier solvent as well as sinter gold nano-particles, thereby yielding conductors of resistivity just slightly higher than bulk gold. Highly selective multi-layered gold nanoparticle film processing was demonstrated using the SPLA-DAT (selective pulsed laser ablation by differential ablation threshold) scheme. This approach enabled definition of narrow channels for FETs (field effect transistors). High performance OFETs (organic field effect transistors) were demonstrated after the final step of semiconductor polymer deposition. Further reduction of feature size has been accomplished via nanoimprinting. The fundamental mechanisms of the nanoparticle sintering process have been investigated by both Molecular Dynamics (MD) simulations as well as in-situ probing.