Cohesively Enhancing the Conductance, Mechanical Robustness, and Environmental Stability of Random Metallic Mesh Electrodes via Hot-Pressing-Induced In-Plane Configuration

Abstract

Flexible transparent conductive electrode (FTCE) is highly desirable due to the fast-growing flexible optoelectronic devices. Several promising FTCEs based on metal material have been developed to replace conventional indium tin oxide (ITO). The random metal mesh is considered to be one of the competitive candidates. However, obtaining feasible random metal mesh with low sheet resistance, high transparency, good mechanical durability, and strong environmental stability is still a great challenge. Here, a random metal mesh-based FTCE with an in-plane structure, achieved by a facile hot-pressing process, is demonstrated. The hot-pressing process enables the fabrication of highly conductive FTCE with improved mechanical robustness and environmental stability. The in-plane FTCE shows a low sheet resistance of 1.63 Ω• sq −1 with an 80.6% transmittance, low relative resistance increase (RRI) of 7.9% after 240 h 85 °C/85% RH test, and low RRI of 8.0% after 10 5 cycles of bending test. Besides, various applications of the in-plane FTCE were demonstrated, including the flexible heater, flexible touch screen, and flexible electroluminescence. We anticipate that these results will spark interest in in-plane random metal mesh electrodes and enable the application of random metal mesh in flexible optoelectronic devices.

Metal nanowire-based transparent electrode for flexible and stretchable optoelectronic devices

“…Hot pressing can also expand the grain size of the metal to improve the conductivity of MNWs. 15 Embedding MNWs into substrates or overlaying a coating layer on a nanowire network are also common methods for 144 The roughness of the original AgNW electrode ranged between 5.96-9.89 nm, whereas that of the embedded AgNW electrode was reduced to 1.23-1.4 nm, which was a notable improvement. The capillary force generated by the shrinkage of the polymer during the embedding and drying of the embedded AgNWs effectively improved the interconnection of the nanowires, resulting in enhanced electrical conductivity.…”

“…To improve the modulus fit between the conductive layer and polymer substrate, the modulus mismatch is usually reduced by adjusting Young's modulus of the substrate or increasing the interface adhesion. 15 Pre-stretching of the substrate is a commonly used method for flexible devices, where the pre-stretched substrate can withstand larger stresses to reduce damage to the functional layers. Gao et al prepared PDMS films on glass substrates and altered the surface wettability by plasma treatment and spraying with hexane.…”

“…Hot pressing can also expand the grain size of the metal to improve the conductivity of MNWs. 15 Embedding MNWs into substrates or overlaying a coating layer on a nanowire network are also common methods for reducing surface roughness. Chu et al compared the effects of different drying methods on the roughness and conductivity of the embedded treated and pristine AgNWs electrodes.…”

“…To improve the modulus fit between the conductive layer and polymer substrate, the modulus mismatch is usually reduced by adjusting Young's modulus of the substrate or increasing the interface adhesion. 15…”

“…13,14 MNW-based FTEs (MFTEs) have demonstrated superior electrical conductivity and higher transmittance compared to ITO-based electrodes, as well as a high yield strength (r2.64 GPa) and excellent figure of merit (FOM, which indicates the relationship between the light transmittance at 550 nm and the sheet resistance). [15][16][17][18] The performance of MFTE-based flexible and stretchable optoelectronic devices has rapidly improved in terms of efficiency and stability, demonstrating promising applications in wearable power sources, displays, and sensors. For example, the power conversion efficiency (PCE) of flexible organic solar cells (OSC) has increased from 10% to 18% in a few years.…”