Fabrication of silver nanowire transparent electrodes at room temperature

Abstract

Silver nanowires (AgNWs) surrounded by insulating poly(vinylpyrrolidone) have been synthesized by a polyol process and employed as transparent electrodes. The AgNW transparent electrodes can be fabricated by heattreatment at about 200 °C which forms connecting junctions between AgNWs. Such a heating process is, however, one of the drawbacks of the fabrication of AgNW electrodes on heat-sensitive substrates. Here it has been demonstrated that the electrical conductivity of AgNW electrodes can be improved by mechanical pressing at 25 MPa for 5 s at room temperature. This simple process results in a low sheet resistance of 8.6 Ω/square and a transparency of 80.0%, equivalent to the properties of the AgNW electrodes heated at 200 °C . This technique makes it possible to fabricate AgNW transparent electrodes on heat-sensitive substrates. The AgNW electrodes on poly(ethylene terephthalate) films exhibited high stability of their electrical conductivities against the repeated bending test. In addition, the surface roughness of the pressed AgNW electrodes is one-third of that of the heat-treated electrode because the AgNW junctions are mechanically compressed. As a result, an organic solar cell fabricated on the pressed AgNW electrodes exhibited a power conversion as much as those fabricated on indium tin oxide electrodes. These findings enable continuous roll-to-roll processing at room temperature, resulting in relatively simple, inexpensive, and scalable processing that is suitable for forthcoming technologies such as organic solar cells, flexible displays, and touch screens.

Flexible transparent conductive materials based on silver nanowire networks: a review

“…Another dependency should be considered for the high-transparency regime where deviation from bulk-like behaviour is observed and can be explained by percolation effects as revealed by the good fit between the dashed lines Reprinted with permission from [118]. (b) Optical transmittance (at 550 nm) versus sheet resistance for graphene [14][15][16][17][18][19], carbon nanotubes [11,[20][21][22][23][24][25][26], AgNWs [27][28][29][30][31][32][33] and ITO [9,11,13]. Solid lines exhibit iso-values of the figure of merit (see text for explanations).…”

Metallic nanowire networks: effects of thermal annealing on electrical resistance

“…Optimizing the electrical resistance and optical transmission of nanowire networks involves tuning several key parameters including the experimental conditions of deposition, wire geometry, 3 network density and post-deposition treatments such as mechanical pressing, 4 light-induced plasmonic nanowelding [5][6][7] or thermal annealing. [8][9][10] All of these postdeposition treatments have been shown to decrease the electrical resistance.…”

Electrical limit of silver nanowire electrodes: Direct measurement of the nanowire junction resistance

“…Therefore, research efforts have focused mainly on reducing the initially high wire-to-wire resistances by several orders of magnitude, e.g., with heating, solvent washing, galvanic treatment, and plasmonic welding. [7][8][9][10][11] However, a detailed study on the basic network parameters has not been performed so far, leaving the question about the theoretical sheet resistance limit of silver nanowire electrodes open.…”