Macroscopic properties of single-crystalline and polycrystalline graphene on soft substrate for transparent electrode applications

Large-area graphene synthesized by a chemical vapor deposition (CVD) method is promising for a flexible, stretchable transparent electrode but suffers from structural defects such as grain boundaries, which causes to degrade its physical properties. Recently, preparation methods of large-scale growth templates for single-crystalline graphene (SCG) were reported, but the macroscopic properties of SCG have not been adequately examined yet. Here, an SCG-based flexible, stretchable graphene transparent electrode is successfully demonstrated, which shows superior optoelectrical, electromechanical, and barrier properties compared to polycrystalline graphene (PCG)-based transparent electrodes. The result exhibits the grain boundary effect of graphene on soft substrates on a macroscopic scale and a great promise toward realizing a tremendous performance improvement of graphene-based flexible transparent electrodes on a large scale. [Display omitted] •The macroscopic properties of SCG and PCG related to transparent electrode application are examined.•SCG and PCG were synthesized and confirmed with various methods both in microscopic and macroscopic scale.•According to the scaling law, graphene without GBs may not have advantages in its physical properties.•The graphene GBs highly affect electromechanical and barrier properties, as well as electrical conductivity.•Using SCG instead of PCG for flexible transparent electrodes is worth it for its improved long-term stability.