Large-Area Cross-Aligned Silver Nanowire Electrodes for Flexible, Transparent, and Force-Sensitive Mechanochromic Touch Screens

Abstract

Silver nanowire (AgNW) networks are considered to be promising structures for use as flexible transparent electrodes for various optoelectronic devices. One important application of AgNW transparent electrodes is the flexible touch screens. However, the performances of flexible touch screens are still limited by the large surface roughness and low electrical to optical conductivity ratio of random network AgNW electrodes. In addition, although the perception of writing force on the touch screen enables a variety of different functions, the current technology still relies on the complicated capacitive force touch sensors. This paper demonstrates a simple and high-throughput bar-coating assembly technique for the fabrication of large-area (>20 × 20 cm), highly cross-aligned AgNW networks for transparent electrodes with the sheet resistance of 21.0 Ω sq at 95.0% of optical transmittance, which compares favorably with that of random AgNW networks (sheet resistance of 21.0 Ω sq at 90.4% of optical transmittance). As a proof of concept demonstration, we fabricate flexible, transparent, and force-sensitive touch screens using cross-aligned AgNW electrodes integrated with mechanochromic spiropyran-polydimethylsiloxane composite film. Our force-sensitive touch screens enable the precise monitoring of dynamic writings, tracing and drawing of underneath pictures, and perception of handwriting patterns with locally different writing forces. The suggested technique provides a robust and powerful platform for the controllable assembly of nanowires beyond the scale of conventional fabrication techniques, which can find diverse applications in multifunctional flexible electronic and optoelectronic devices.

Fused silver nanowires with silica sol nanoparticles for smooth, flexible, electrically conductive and highly stable transparent electrodes

“…For 8 nm silica sol nanoparticles, when the concentration of silica sol increases to 80 ppm, the AgNWs ink contains a huge number of nanoparticles with diameter of 8 nm, which fully decorate the surface of the AgNWs, affording AgNWs with larger diameter. According to previous research, [49][50][51] the transmittance of TCEs is related to the area coverage A c as shown in eqn (1) and (2). Therefore, with increasing diameter of AgNWs, the A c increases, and the transmittance decreases.…”

“…At present, AgNWs can be easily synthesized using the well-established polyol reduction method in the presence of polyvinylpyrrolidone (PVP), [23][24][25] but the residual PVP ligands will form an insulating layer around the AgNWs, resulting in high contact resistance at NW-NW junctions. A number of strategies have been developed to improve the conductivity of AgNWs thin lms, including mechanical pressing, 26,27 plasmonic welding, 10,28 thermal annealing, 27,29,30 adding soldering agents, [31][32][33] capillary-force-induced cold welding, 34 nanowire assembly, 2,35 and photochemical welding. 36,37 However, these strategies either need harsh conditions or are not efficient enough for large area fabrication.…”

Conductive Hydrogels as Smart Materials for Flexible Electronic Devices

“…[95,96] However,i ts stiff and brittle properties limit its further progressi nf lexible touch devices because the future touch panelss hould be stretchable or at least flexible in order to interact with human body.T herefore,s ome candidates, such as metal nanostructures, graphene, CNTs, and conductingp olymers, are investigating to displace indium tin oxide for their combinationo fh igh conductivity and stretchability. [97][98][99][100][101][102][103][104] For example, ah ighly flexible and transparent conductor was fabricated by using Ag nanowirea nd conducting polymer. [105] The neighboring Ag nanowires weren anosoldered by PEDOT:PSS coating at the nanowire junctions, whichr educed contacting resistance of the hybrid composite film.…”

Extremely lightweight and ultra-flexible infrared light-converting quantum dot solar cells with high power-per-weight output using a solution-processed bending durable silver nanowire-based electrode

“…Therefore, the Ag NWs are believed to be one of the most promising electrode materials for the flexible photovoltaic or optoelectronic devices. [39][40][41][42] The performance of the metal NW-based electrode generally increases with the decrease in the diameter of the NW, while the increase in the NW length/diameter aspect ratio will reduce light scattering and decrease the resistance in the film. [43][44][45][46][47][48][49] Therefore, in this study, Ag NWs with an average aspect ratio of 5000 (average diameter of B30 nm and length of 100-200 um, Fig.…”