Nanoscale Joule Heating and Electromigration Enhanced Ripening of Silver Nanowire Contacts

Abstract

Solution-processed metallic nanowire thin film is a promising candidate to replace traditional indium tin oxide as the next-generation transparent and flexible electrode. To date however, the performance of these electrodes is limited by the high contact resistance between contacting nanowires; so improving the point contacts between these nanowires remains a major challenge. Existing methods for reducing the contact resistance require either a high processing power, long treatment time, or the addition of chemical reagents, which could lead to increased manufacturing cost and damage the underlying substrate or device. Here, a nanoscale point reaction process is introduced as a fast and low-power-consumption way to improve the electrical contact properties between metallic nanowires. This is achieved via current-assisted localized joule heating accompanied by electromigration. Localized joule heating effectively targets the high-resistance contact points between nanowires, leading to the automatic removal of surface ligands, welding of contacting nanowires, and the reshaping of the contact pathway between the nanowires to form a more desirable geometry of low resistance for interwire conduction. This result shows the interplay between thermal and electrical interactions at the highly reactive nanocontacts and highlights the control of the nanoscale reaction as a simple and effective way of turning individual metallic nanowires into a highly conductive interconnected nanowire network. The temperature of the adjacent device layers can be kept close to room temperature during the process, making this method especially suitable for use in devices containing thermally sensitive materials such as polymer solar cells.

Electrical, mechanical and thermal properties of aligned silver nanowire/polylactide nanocomposite films

“…Once multiple twin Ag particles are formed, due to energy difference between {100} and {111} planes, {111} surfaces of the particles are completely covered with PVP and fresh Ag þ ions deposit onto the free {100} surfaces, resulting in 1D anisotropic growth [32]. Although this thin PVP layer increases the NW-NW junction resistance, it is useful to achieve stable dispersions of Ag NWs in different media like water, acetone and ethanol [33]. Fig.…”

Multilayer Transparent Top Electrode for Solution Processed Perovskite/Cu(In,Ga)(Se,S)2 Four Terminal Tandem Solar Cells

“…[31][32][33] Most of these possibilities are obtainable through solution-processing or wettransfer techniques. 31,34 though proven to be successful in organic devices, these transparent conductors are challenging to implement into the PVSK system since the polar solvent used to disperse such transparent conductors usually dissolves the PVSK materials, as PVSK is a polar semiconductor. To this date, transparent top electrodes have been successfully applied in PVSK solar cells via a limited number of approaches.…”

Water-bath assisted convective assembly of aligned silver nanowire films for transparent electrodes

“…A 150 µL prepared AgNW isopropanol dispersion was added onto the hot water surface drop by drop using a pipette. The location of drop 25 was kept near the center of the water surface to make AgNWs spread out effectively. 1.5×1.5 cm 2 glass substrates were cleaned with acetone, deionized water and isopropanol each for 10 min in ultrasonic bath.…”

“…Recent research has focused on several 20 alternatives including conductive polymers, 1 carbon nanotubes, 2-5 grapheme, 6,7 metal grids 8 and silver nanowires (AgNWs). [9][10][11] Among them, AgNWs with its high conductivity, excellent flexibility and solution processing have proven to be the most promising candidate alternative to ITO and competing 25 amorphous oxides. 12 AgNW network can be achieved by many means such as spin-coating, 13,14 drop-casting, 9,15 rod-coating 16,17 and spraying-coating.…”