Selective Growth and Integration of Silver Nanoparticles on Silver Nanowires at Room Conditions for Transparent Nano-Network Electrode

Abstract

Recently, metal nanowires have received great research interests due to their potential as next-generation flexible transparent electrodes. While great efforts have been devoted to develop enabling nanowire electrodes, reduced contact resistance of the metal nanowires and improved electrical stability under continuous bias operation are key issues for practical applications. Here, we propose and demonstrate an approach through a low-cost, robust, room temperature and room atmosphere process to fabricate a conductive silver nano-network comprising silver nanowires and silver nanoparticles. To be more specific, silver nanoparticles are selectively grown and chemically integrated in situ at the junction where silver nanowires meet. The site-selective growth of silver nanoparticles is achieved by a plasmon-induced chemical reaction using a simple light source at very low optical power density. Compared to silver nanowire electrodes without chemical treatment, we observe tremendous conductivity improvement in our silver nano-networks, while the loss in optical transmission is negligible. Furthermore, the silver nano-networks exhibit superior electrical stability under continuous bias operation compared to silver nanowire electrodes formed by thermal annealing. Interestingly, our silver nano-network is readily peeled off in water, which can be easily transferred to other substrates and devices for versatile applications. We demonstrate the feasibly transferrable silver conductive nano-network as the top electrode in organic solar cells. Consequently, the transparent and conductive silver nano-networks formed by our approach would be an excellent candidate for various applications in optoelectronics and electronics.

Towards low cost materials and methods for transparent electrodes

“…Coleman and coworkers were the first to use Ag nanowire networks as transparent electrodes and achieved 85% transmittance with sheet resistance of 13 V/sq [36]. Many researches have attempted to minimize junction resistances of nanowire networks (Figure 2) [38][39][40] by decreasing the density of the junctions or by post annealing or plasmonic welding. Flexible organic solar cells, fabricated with Ag nanowires were highly stable even to a bending radius of 200 mm [41].…”

Light welding nanoparticles: from metal colloids to free-standing conductive metallic nanoparticle film

“…Therefore, interfacial self-assembly is also a powerful bottom-up strategy to make functional unit of the nanoscale devices from NPs [19]. However, such solution-assembled NP thin films are often plagued by excessive inter-particle resistance that limits current delivering capability [20,21], which has severely limited their application as conductive electrodes in advanced electronic and optoelectronic devices.…”

Comprehensive Synthesis Study of Well-Dispersed and Solution-Processed Metal Nanowires for Transparent Heaters

“…As a predeposition treatment, the as-synthesized wires are usually centrifuged 1-3 times in acetone and subsequently in either ethanol or water to remove EG and PVP [6,33,42]. As a postdeposition treatment, methods such as thermal sintering [56][57][58], photonic sintering [59][60][61], immersion in water [38], applying a conductive coating such as PEDOT:PSS [62][63][64], selective growth of silver nanoparticles at the AgNW junctions [65], and cold welding by applying a mechanical pressure [38,52,66] have been reported. The performance of a TCE is conventionally assessed by looking to the transmittance of the electrode at a wavelength of 550 nm and the sheet resistance.…”