An organic light-emitting diode includes a first electrode and a second electrode that face each other, an organic emission layer between the first electrode and the second electrode, and an inorganic hole injection layer between the first electrode and the organic emission layer. The inorganic hole injection layer includes oxide of a form A-B-O, including an element A and an element B. The element A is one of molybdenum (Mo) and tungsten (W). The element B is one of vanadium (V), niobium (Nb), and tantalum (Ta). An atom content (x) of the element B is greater than 0 and no more than 15 at % (0