Chemically Robust Indium Tin Oxide/Graphene Anode for Efficient Perovskite Light-Emitting Diodes.

Graphene is an optimal material to be employed as an ionic diffusion barrier because of its outstanding impermeability and chemical robustness. Indium tin oxide (ITO) is often used in perovskite light-emitting diodes (PeLEDs), and it can release indium easily upon exposure to the acidic hole-injection layer so that luminescence can be quenched significantly. Here, we exploit the outstanding impermeability of graphene and use it as a chemical barrier to block the etching that can occur in ITO exposed to an acidic hole-injection layer in PeLEDs. This barrier reduced the luminescence quenching that these metallic species can cause, so the photoluminescence lifetime of perovskite film was substantially higher in devices with ITO and graphene layer (87.9 ns) than in devices that had only an ITO anode (22.1 ns). Luminous current efficiency was also higher in PeLEDs with a graphene barrier (16.4 cd/A) than in those without graphene (9.02 cd/A). Our work demonstrates that graphene can be used as a barrier to reduce the degradation of transparent electrodes by chemical etching in optoelectronic devices.