Organic el device
An organic EL device is disclosed that has a buffer layer that prevents degradation of a reflection electrode and an electron injection layer due to chemical reaction between the material of the reflection electrode and the material of the electron injection layer when the two materials are in contact with each other. The buffer layer also prevents movement of the material of the reflection electrode into an organic EL layer. The buffer layer further allows reduction of a driving voltage of the organic EL device. An organic EL device of the invention includes a transparent electrode, an organic EL layer including at least an organic light emitting layer and an electron injection layer, a buffer layer, and a reflection electrode laminated on a substrate in this order. The electron injection layer is in contact with the buffer layer and doped with an alkali metal or an alkaline earth metal. The buffer layer is formed from a conductive material that does not form an alloy with the material of the reflection electrode.
1 . An organic EL device comprising
a substrate,
a transparent electrode formed on the substrate,
an organic EL layer formed on the transparent electrode, the organic EL layer including at least an organic light emitting layer and an electron injection layer,
a buffer layer formed on the organic EL layer, and
a reflection electrode formed on the buffer layer,
wherein the electron injection layer is in contact with the buffer layer and doped with an alkali metal or an alkaline earth metal and the buffer layer is formed of a conductive material that prevents alloying with a material contained in the reflection electrode.
2 . The organic EL device according to claim 1 , wherein the buffer layer prevents chemical reaction between a material of the electron injection layer and a material of the reflection electrode.
3 . The organic EL device according to claim 2 , wherein the material contained in the buffer layer is selected from noble metals, conductive metal oxides, and conductive metal nitrides.
4 . The organic EL device according to claim 3 , wherein the buffer layer contains a noble metal selected from a group consisting of Au, Pt, Ag, and Pd.
5 . The organic EL device according to claim 3 , wherein the conductive metal oxide is selected from a group consisting of RuO 2 , ITO, SnO 2 , IZO, TiO 2 , ReO 3 , V 2 O 3 , MoO 2 , and PtO 2 .
6 . The organic EL device according to claim 3 , wherein the conductive metal nitride is selected from a group consisting of TiN, ZrN, and TaN.
7 . The organic EL device according to claim 1 , wherein a thickness of the buffer layer is in a range of 0.5 to 100 nm.
8 . The organic EL device according to claim 1 , wherein reflectivity of the reflection electrode is at least 90%.
9 . The organic EL device according to claim 1 , wherein the material contained in the reflection electrode is aluminum or silver.