Super-Joule heating in graphene and silver nanowire network

Abstract

Transistors, sensors, and transparent conductors based on randomly assembled nanowire networks rely on multi-component percolation for unique and distinctive applications in flexible electronics, biochemical sensing, and solar cells. While conduction models for 1-D and 1-D/2-D networks have been developed, typically assuming linear electronic transport and self-heating, the model has not been validated by direct high-resolution characterization of coupled electronic pathways and thermal response. In this letter, we show the occurrence of nonlinear “super-Joule” self-heating at the transport bottlenecks in networks of silver nanowires and silver nanowire/single layer graphene hybrid using high resolution thermoreflectance (TR) imaging. TR images at the microscopic self-heating hotspots within nanowire network and nanowire/graphene hybrid network devices with submicron spatial resolution are used to infer electrical current pathways. The results encourage a fundamental reevaluation of transport models for network-based percolating conductors.

Copercolating Networks: An Approach for Realizing High-Performance Transparent Conductors using Multicomponent Nanostructured Networks

“…Here, the graphene works as a barrier to moisture to prevent oxidation and corrosion. Experiments show stable resistance even after years of exposure to moisture [20,61].…”

“…Self-heating in nanonet TCEs have been characterized carefully and in detail. It has been demonstrated that percolation plays an important role in heat conduction in these networks [63], the thermal bottlenecks are reflected in the formation of hotspots and the heating in these hotspots scales superlinearly with current [61], and most importantly, hotspots may eventually seed the fracture of the film [77]. Obviously, self-heating will accelerate oxidation and corrosion of the films.…”

“…Another superior property of hybrid networks is improved heat spreading with respect to that of percolating networks [61][62][63]. Metal nanowire network-based percolating structures are prone to developing self-heated hotspots that originate primarily from nanowire -nanowire junctions and from conduction through the bodies of the nanowires.…”

“…Recently, a number of applications of hybrid AgNW-graphene have been demonstrated in the literature ranging from its use as electrodes in light-emitting diodes to atomically thin barrier layer for protection against high-energy radiation [21,29,30,[52][53][54][55][56][57][58][59][60][61]. The schematic shown in Figure 6 summarizes the recent progress in the field and Table 2 presents their key physical properties.…”

“…The presence of graphene also enables injection of higher current density into the structure, making it robust for applications such as transparent heaters, wind shield glass heater, advanced interconnect structures, etc. [61,[64][65][66].…”