An OLED device comprising, in sequence, an anode, a light-emitting layer that comprises a phosphorescent light-emitting organometallic compound, a hole-blocking layer, and a cathode, and between the hole-blocking layer and the cathode, a further layer containing a mixture of a first compound that is a tetracene compound that has the lowest LUMO value of the compounds in the layer, in an amount greater than or equal to 10% and less than 90% and a second compound that is a low voltage electron transport material, exhibiting a higher LUMO value than the first compound in an amount less than or equal to 90% and more than 10%.