Transfer Medium Design for Fabrication of Graphene Barrier Films

Theoretically, defect-free monolayer graphene grown by chemical vapor deposition can block nearly all gases and moisture, making it a promising material for large-scale flexible encapsulation in future photonic and electronic applications. However, the lack of reliable transfer and fabrication methods that suppress the formation of transfer-induced cracks and interlayer transport of water molecules in stacked graphene films severely limits the barrier performance of current graphene-based barrier films. In this work, we employed a dopant-incorporated polyvinylidene difluoride with a concentration gradient as a transfer medium to suppress crack formation during transfer through conformal graphene-polymer contact and to dope graphene, thereby hindering water diffusion through enhanced water-graphene interactions. Consequently, the as-fabricated barrier film achieved an ultralow water vapor transmission rate value of 9.3 × 10-5 g m-2 day-1. In addition, a home-built roll-to-roll transfer system for continuous fabrication of graphene barrier films demonstrates the scalability of this strategy and its potential for large-scale flexible and transparent encapsulation.