Organic electroluminescent element, illumination device, and display device

An organic electroluminescent element, comprising:

• a light transmissive substrate;
• a light emitting stack including a first electrode that is light transmissive, a light emitting layer, and a second electrode which are arranged in this order from the light transmissive substrate;
• and
• at least one light-outcoupling structure which is provided closer to a light-outcoupling side, which is a side opposite the first electrode with respect to the light emitting layer, than the first electrode and has an uneven structure,
• the light emitting layer having a birefringence property which exhibits a higher refractive index in a direction parallel to a surface of the light transmissive substrate than a refractive index in a direction perpendicular to the surface of the light transmissive substrate,
• the uneven structure including a plurality of protrusions of substantially a same height which are allocated to first sections selected from planar grid-like sections so that the planar grid-like sections become uneven,
• the uneven structure including
• unit regions each of which corresponds to a total area of adjacent sections in a planar view, selected from the planar grid-like sections,
• each of the unit regions including the same number of adjacent sections,
• the adjacent sections including at least one section selected from the first sections, so that each of the unit regions includes at least one protrusion selected from the plurality of protrusions on the first sections, and
• an area of the at least one protrusion in each of the unit regions being substantially a same in a planar view.