Flexible transparent conductive coatings by combining self-assembly with sintering of silver nanoparticles performed at room temperature

Abstract

Transparent conductive coatings are essential for fabrication of a variety of printed electronic devices such as flexible displays and solar cells. We report on a simple method to obtain such coatings by using aqueous dispersions of silver nanoparticles in an evaporative lithography process which is performed directly onto plastic substrates. In essence, a droplet containing silver nanoparticles is placed on top of a metallic mesh, instantaneously spreading over the mesh and the plastic substrate, and after the flow of the dispersion towards the wires of the mesh and drying, a transparent grid composed of the nanoparticles is formed. The silver nanoparticles are tailored to self-sinter upon short exposure to HCl vapors, due to the presence of polyacrylic acid salt on the surface of the particles. Therefore, immediate sintering of the silver nanoparticles in the thin lines of the grid occurs even at room temperature, enabling formation of transparent, flexible conductive grid on heat-sensitive substrates. The process yielded a conductive array having a very low sheet resistance, 9 AE 0.8 U/,, and a transparency above 75%. The application of the flexible conductive grid, which can replace conventional and expensive ITO, is demonstrated in an electroluminescent (EL) device.

Nonequilibrium kinetic modeling of sintering of a layer of dispersed nanocrystals

“…The use of nanoparticles can improve the connectivity (conductance) 4 in sintering of layers including noble metal nanocrystals that are dispersed [2][3][4][5][6]8,[24][25][26][27][28] in paste-like materials containing other additives. The crystalline nanoparticles can be uniform or distributed in their sizes and shapes, ranging from even-proportioned, approximately spherical shapes, to flake-shaped or needleshaped particles.…”

“…[1][2][3][4][5][6][7][8][9] Sintering was also modelled by using several approaches [10][11][12][13][14][15][16][17][18][19][20][21][22][23] ranging from continuum theories to mesoscopic statistical-mechanical approaches. These studies have yielded information of the structure of the sintered materials, as well as on more local properties morphological properties such as neck formation and particle merging.…”

Bio-inspired networks for optoelectronic applications

“…However, while metal-oxides often have desirable electro-optical properties, they are also brittle, and this deficiency limits their usefulness in many practical applications. To address these challenges, new approaches have been recently devised, based on metallic micro-and nanoscaffoldings (such as wire and nanowire grids [3][4][5][6][7][8][9][10] , nanoparticles 11,12 and so on) and even using atomicscale scaffolds such as graphene 13,14 . Structures of this kind do in fact improve mechanical flexibility, but their electro-optical performance has not yet been sufficiently high.…”

Novel Hybrid Electrode Using Transparent Conductive Oxide and Silver Nanoparticle Mesh for Silicon Solar Cell Applications

“…Owing to the good electrical properties of the silver mesh, which are superior to those of silver nanowire and nanoparticle meshes reported previously [12,15], the lateral conductance of the hybrid structures is greatly reduced by one order of magnitude, with only a moderate reduction in the optical transmission. Our hybrid structure also has a higher lateral conductance and transparency than the hybrid structures formed by silver nanowires (using either carbon nanotubes [26] or titanium dioxide [27]).…”

“…nanoparticles, nanowires). Commonly used patterning methods include lithography [11,12] and direct writing methods by inkjet printing [13,14]. The patterning methods are able to form regular and periodic structures, with an accurate control of the network line width down to the nanoscale range; however they are limited to small-area devices due to the complex and time-consuming fabrication processes.…”