Graphene-encapsulation effect of BaTiO3 on AC electroluminescence

Alternating current (AC) driven inorganic electroluminescence (EL) was investigated with a focus on the polymer-based dielectric layer, where barium titanate (BTO) powder particles encapsulated in reduced graphene oxide (rGO) platelets. The EL devices with rGO-encapsulated BTO exhibited higher luminescence and lower current density than the non-encapsulated case with BTO only, primarily due to enhanced dielectric performance of the dielectric layer. This was originated from the encapsulation of BTO in rGO platelets through the interfacial polarization of numerous micro-capacitors within the dielectric layer. By varying the concentration of rGO (0, 0.05, 0.10, and 0.20 wt%), the optimum concentration of encapsulated rGO was found to be near 0.10 wt%, where the highest concentration case (0.20 wt%) showed the worst EL performance, possibly due to crisscross linking among rGO-encapsulated BTO. We found that the quality of the dielectric layer, if the optimum concentration of graphene was employed, was a key factor in AC EL.