US Patent 9368744 Organic light emitting diode device including multiple hole injection layers

An organic light emitting diode device, including a first electrode, a second electrode facing the first electrode, and a light emitting member disposed between the first electrode and the second electrode, the light emitting member including at least one light emitting unit. At least one of the light emitting units may include a first hole injection layer, a second hole injection layer, a hole transport layer, and an emission layer, and a difference between a HOMO energy level of the first hole injection layer and a LUMO energy level of the second hole injection layer may be smaller than about 0.5 eV.