Patent ID: 8866130

Claim:
A light-emitting device comprising: an organic electroluminescent element of a double-side emission type having a first transparent electrode layer, a light-emitting layer, and a second transparent electrode layer provided in this order; and a light output surface structure layer provided directly or indirectly on at least one surface of the organic electroluminescent element, wherein the light output surface structure layer includes a concavo-convex structure on a surface opposite to the organic electroluminescent element, the concavo-convex structure having flat surface portions parallel to one surface of the organic electroluminescent element and an inclined surface portion tilted relative to the flat surface portions, a projected area formed by projecting the inclined surface portion in a direction perpendicular to the flat surface portions onto a plane parallel to the flat surface portions is equal to or less than 0.1 times a total area of the flat surface portions, and the flat surface portions have a specific flat surface portion with a ratio H/W of 1 or greater and 2.5 or less, where H and W are a height and a width of the specific flat surface portion, respectively, on a cross section thereof cut along a plane parallel to a width direction and a thickness direction thereof.