Deformation-induced cold-welding for self-healing of super-durable flexible transparent electrodes

Flexible transparent electrodes (FTEs) are key elements in flexible photoelectronics. The durability of FTEs is determined by two effects caused by deformations: the damage effect, and the recovery effect. The damage effect, that under how much strain and how many cycles an FTE can be destroyed, has been investigated in a few existing works. However, people did not perform any systematic studies on the recovery effect of FTEs and has not yet realized its importance. Herein, we demonstrate that metallic nanowires may recover with strain cycling. Pre-damaged Au nanomesh FTEs can recover under cyclic strains due to the spontaneous cold-welding of fractured nanowires by natural relaxing, or cyclic compressing, or cyclic stretching (with a strain up to 70%), or random deformations within modest strain ranges. Under small tensile strains (<10%), recovery still happens after thousands of cycles. The microscopic observations show that the two-dimensional mesh selectively heals at the fractured points. The stretch-induced cold-welding lies in two aspects: the superplasticity of Au nanowires, and the suitable adhesion between Au and the underlying elastomeric substrate. Our findings indicate that the pre-damaged FTEs can largely restore its original state during its practical applications, which means that the Au nanonnesh FTEs are very durable, a much desired feature in the flexible photoelectronic industry. Published by Elsevier Ltd.