Organic EL element, display panel, and display device
View Patent ↗An organic EL element comprises: a transparent electrode; a reflective electrode opposite the transparent electrode; and a light-emitting layer having a film thickness of 20 nm to 200 nm, between the electrodes. The reflective electrode is a layered film of: a metal film including Al as a main component and having a film thickness of at least 43 nm; and a Ni film, whose film thickness d satisfies: 0 nm<d <5 nm, layered with respect to an entirety of a surface, facing the light-emitting layer, of the metal film, without interposition of an oxide layer that covers the surface of the metal film entirely. A surface of the layered film facing the light-emitting layer has an average roughness Ra satisfying: 0.6 nm≦Ra<2.0 nm and a maximum height difference Rmax satisfying: 5 nm≦Rmax<20 nm.
1. An organic EL element, comprising:
a transparent electrode;
a reflective electrode opposite the transparent electrode; and
a light-emitting layer between the transparent electrode and the reflective electrode, the light-emitting layer having a film thickness of 20 nm to 200 nm, wherein
the reflective electrode is a layered film of:
a metal film including Al as a main component, the metal film having a film thickness of at least 43 nm; and
a Ni film layered with respect to the metal film at surfaces thereof including a surface of the metal film facing the light-emitting layer and external side surfaces of the metal film, without interposition of an oxide layer that covers the surfaces of the metal film,
a film thickness d of the Ni layer satisfies: 0 nm <d <5 nm,
an average roughness Ra of a surface of the layered film facing the light-emitting layer satisfies: 0.6 nm ≦Ra <2.0 nm,
a maximum height difference Rmax of the surface of the layered film satisfies: 5 nm ≦Rmax <20 nm, and
the external side surfaces of the metal film do not face the light-emitting layer.
2. The organic EL element of claim 1 , wherein the maximum height difference Rmax satisfies: 5 nm <Rmax <17 nm.
3. The organic EL element of claim 1 , wherein the reflective electrode is provided in plurality, the organic EL element further comprising
a bank defining a plurality of apertures each corresponding to one of the reflective electrodes, wherein
the light-emitting layer is provided in plurality such that each light-emitting layer is positioned inside a corresponding one of the apertures, and
both end portions of each reflective electrode are covered by the bank at least in one cross-sectional direction through the reflective electrode.
4. The organic EL element of claim 1 , wherein oxide films are formed on the surface of the metal film facing the light-emitting layer as discrete islands or as portions of a discontinuous film.
5. The organic EL element of claim 1 , further comprising
a transparent conductive film between the reflective electrode and the light-emitting layer.
6. The organic EL element of claim 5 , wherein
the transparent conductive film comprises ITO, IZO, or a metal oxide other than ITO or IZO.
7. The organic EL element of claim 1 , further comprising
a charge injection layer between the reflective electrode and the light-emitting layer.
8. The organic EL element of claim 7 further comprising
a charge transport layer between the charge injection layer and the light-emitting layer.
9. The organic EL element of claim 7 , wherein
the charge injection layer is a layer that comprises a metal oxide, a metal nitride, or a metal oxynitride.
10. The organic EL element of claim 7 , wherein
the charge injection layer is a layer that comprises tungsten oxide or molybdenum oxide.
11. A display panel comprising the organic EL element of claim 1 .
12. The organic EL element of claim 1 , wherein
the Ni film is a continuous film covering the surfaces of the metal film including the surface facing the light-emitting layer and the external side surfaces.
13. An organic EL element, comprising:
a transparent electrode;
a reflective electrode opposite the transparent electrode; and
a light-emitting layer between the transparent electrode and the reflective electrode, the light-emitting layer having a film thickness of 20 nm to 200 nm, wherein
the reflective electrode is a layered film of:
a metal film including Al as a main component, the metal film having a film thickness of at least 43 nm; and
a Ni film layered with respect to the metal film at surfaces thereof including surface of the metal film facing the light-emitting layer and external side surfaces of the metal film, without interposition of an oxide layer that covers the surfaces of the metal film,
a film thickness d of the Ni layer satisfies: 0 nm <d <5 nm,
an average roughness Ra of a surface of the layered film facing the light-emitting layer satisfies: 0.6 nm ≦Ra <2.0 nm,
a maximum height difference Rmax of the surface of the layered film satisfies: 5 nm ≦Rmax <20 nm, and
the Ni film is a film of Ni deposited through electroless plating processing.
14. A display panel having a plurality of pixels, comprising:
a reflective electrode for each of the plurality of pixels;
a bank defining an aperture corresponding to the reflective electrode;
a light-emitting layer positioned inside the aperture; and
a transparent electrode above the light-emitting layer, wherein
the bank covers both end portions of the reflective electrode at least in one cross-sectional direction through the reflective electrode,
the reflective electrode is a layered film of:
a metal film including Al as a main component, the metal film having a film thickness of at least 43 nm; and
a Ni film layered with respect to the metal film at surfaces thereof including a surface of the metal film facing the light-emitting layer and external side surfaces of the metal film, without interposition of an oxide layer that covers the surfaces of the metal film,
a film thickness d of the Ni layer satisfies: 0 nm <d <5 nm,
an average roughness Ra of the surface of the metal film satisfies: 0.6 nm ≦Ra <2.0 nm,
a maximum height difference Rmax of the surface of the metal film satisfies: 5 nm ≦Rmax <20 nm, and
the external side surfaces of the metal film do not face the light-emitting layer.
15. The display panel of claim 14 , wherein
the aperture is provided in plurality so as to correspond one-to-one with a plurality of reflective electrodes.
16. The display panel of claim 14 , wherein
the plurality of reflective electrodes are arranged so as to form a plurality of lines, and
the aperture is provided in plurality so as to correspond one-to-one with the plurality of lines of the plurality of reflective electrodes.
17. A display device comprising the display panel of claim 14 .
18. The display panel of claim 14 , wherein
the Ni film is a continuous film covering the surfaces of the metal film including the surface facing the light-emitting layer and the external side surfaces.