Single Step Laser Transfer and Laser Curing of Ag NanoWires: A Digital Process for the Fabrication of Flexible and Transparent Microelectrodes

Abstract

Ag nanowire (NW) networks have exquisite optical and electrical properties which make them ideal candidate materials for flexible transparent conductive electrodes. Despite the compatibility of Ag NW networks with laser processing, few demonstrations of laser fabricated Ag NW based components currently exist. In this work, we report on a novel single step laser transferring and laser curing process of micrometer sized pixels of Ag NW networks on flexible substrates. This process relies on the selective laser heating of the Ag NWs induced by the laser pulse energy and the subsequent localized melting of the polymeric substrate. We demonstrate that a single laser pulse can induce both transfer and curing of the Ag NW network. The feasibility of the process is confirmed experimentally and validated by Finite Element Analysis simulations, which indicate that selective heating is carried out within a submicron-sized heat affected zone. The resulting structures can be utilized as fully functional flexible transparent electrodes with figures of merit even higher than 100. Low sheet resistance (<50 Ohm/sq) and high visible light transparency (>90%) make the reported process highly desirable for a variety of applications, including selective heating or annealing of nanocomposite materials and laser processing of nanostructured materials on a large variety of optically transparent substrates, such as Polydimethylsiloxane (PDMS).

Screen printing of silver nanowires: balancing conductivity with transparency while maintaining flexibility and stretchability

“…The middle and right panels of 8,57 drop coating, 30 spin coating, 32 spray coating, 43 and Mayer rod coating 13,31 ) and one-step printing methods (ground color of purple) (electrohydrodynamic printing, 49 additive printing, 58 screen printing, 25 inkjet printing, 34 and seed particle printing 59 ), as well as some other transparent conductors (ground color of green) through direct writing of silver nanoparticles (Ag NPs), 60 copper random network, 61 direct printing of Ag precursors, 50 and laser transferring. 51 Note: For the printed Ag NW patterns in the literature, where the transmittance values at the wavelength of 550 nm are not clearly mentioned, the FoMs have been estimated based on the film thicknesses and the physical appearance of the patterns in comparison to our work. b Schematics for the process to achieve high transparency and conductivity for the printed Ag NW films in this work.…”

“…For comparison's sake, other studies have reported the following sheet resistance and transmittance values: screen-printed Ag NW patterns (calculated sheet resistance, 1.05 ohm/sq; no transparency data), 25 gravureprinted Ag NW patterns (calculated sheet resistance, 0.468 ohm/ sq; no transparency data), 48 electrohydrodynamic printed Ag NW patterns (sheet resistance, 1.5-3.7 ohm/sq; no transparency data), 49 direct printing of Ag precursor (sheet resistance, 27.6 ohm/sq; transmittance: 94.7%), 50 and laser transferred Ag NW patterns (sheet resistance, 59.1 ohm/sq; transmittance: 92.3%). 51 To further highlight the influence of laser sintering on the properties of transparent patterns, we calculated and plotted the FoM of the printed Ag NW patterns before and after laser sintering, as illustrated in Fig. 3b.…”

Laser-Induced Forward Transfer Applications in Micro-engineering

“…7b. Zacharatos et al have also recently shown the use of LIFT for AgNW electrodes (Zacharatos et al 2018). In this work, AgNW suspensions are transferred directly in the solid phase under low vacuum onto the receiving substrate without the use of a sacrificial layer.…”

Copper micro-electrode fabrication using laser printing and laser sintering processes for on-chip antennas on flexible integrated circuits

“…After the laser printing process is over, a sintering process is required so that the copper ink patterns obtain the desired electrical properties. In this work we have employed laser sintering for selective and high resolution heating of the nanoparticles, as it is extensively described in previous works [9][10][11]. First the printed ink dries in ambient atmosphere for a few minutes at room temperature, then the sintering procedure takes place with the direct exposure of the pattern to the laser beam ( Fig.…”

“…One of the most widely used additive micro-manufacturing technologies relies on the direct printing followed by selective sintering of metal nanoparticle inks. Laser printing relying on the Laser Induced Forward Transfer (LIFT) technique, combined with selective laser sintering stand out among the additive micro-manufacturing technologies [3][4][5] owing to the high speed (>1 m/s) and high resolution (<50 µm) [6], as well as the lateral selectivity and minimized heat affected zone with demonstrations of highly conductive micro-patterns in flexible electronic applications [7][8][9][10][11]. In this technology, inks comprising metals like gold and silver have been primarily employed due to their high conductivity and environmental stability [12].…”