The project concerns the fabrication of high-performance flexible electronics by utilizing laser processing of nanoparticle suspensions in conjunction with direct micro-printing. Laser sintering and ablation of inkjet printed metal nanoparticles enables low temperature metal deposition as well as high-resolution patterning, thus overcoming the resolution limitation of inkjet direct writing without any lithography processes. Combined with air stable carboxylate-functionalized polythiophene, all-printed and laser processed organic field effect transistors (OFETs) with micron to submicron critical feature resolution will be fabricated in a fully maskless sequence, eliminating the need for any lithographic processes. All processing and characterization steps will be carried out at plastic-compatible low temperatures. The fabricated devices will be characterized in order to optimize the performance in terms of the channel size, the air stable semiconductor material, the short channel effect and the channel roughness. To increase reliability, the thickness uniformity of the printed dielectric layer will be improved. For fundamental understanding and ultimately for process optimization, both experimental and theoretical investigations will be conducted on the physical mechanisms of the laser light interaction with the nanoparticle material. Temporally and spectrally resolved monitoring techniques, including far-field and near-field optical probing will be performed to interrogate the phase transition, particle deformation, sintering and ablation processes. In-situ transmission electron microscopy (TEM) studies will carried out to directly image the bonding sequence with nanometer resolution. Molecular dynamics (MD) simulations will be carried out in coordination with the experimental work to investigate the phase transition and sintering processes. To facilitate the numerical simulations, thermal, optical and electrical properties of the nanomaterial will be measured. Broader Impact The reduced temperature, laser-based processing of metal nanoparticles eliminates the need for lithographic processes and opens the way to the low-cost, maskless fabrication of high-resolution, electronic devices on flexible substrates. Prime candidates for the utilization of the technology developed in this project include the manufacture of displays and large area electronics, interconnections, crossover conductors, capacitors, antennae, chemical sensors and active electrical components on flexible substrates. A spectrum of potential applications can be envisioned for the fabrication of sensors and devices based on magnetic, ceramic and semiconductor nanoparticles. The scientific research outcome is expected to shed light on complex phenomena involved in the laser interactions with nanoparticle materials. Specifically, it will elucidate the energy transfer, melting, sintering and ablation processes under laser excitation.
