Enhanced gas barrier property of stacking-controlled reduced graphene oxide films for encapsulation of polymer solar cells

Abstract

Compact stacking of building blocks is essential in order to utilize the impermeable nature of reduced graphene oxide (rGO) for encapsulating barriers in organic electronics. To obtain the desired accumulation characteristic, rGO films were fabricated via spraying process using phase-controlled graphene oxide (GO) dispersion. The rGO laminate prepared from the isotropic-phase dispersion exhibits a more favorable face-on orientation of rGO building blocks than that from the nematic-phase GO, which implies effective stacking of building blocks. As a result, the resulting gas barrier performance of the low-temperature-annealed rGO film is superior to previously reported low-temperature solution-processed materials. Fabricated gas barriers are adopted to seal the polymer solar cell with 57.2 times longer lifetime than that of the unsealed device. A device covered by an optimized rGO/polyethylene naphthalate gas barrier maintains photovoltaic performance as high as 88% of the initial efficiency after 28 days.