Patent ID: 8530908

Claim:
An organic EL element comprising: an organic EL layer including a transparent electrode, a reflective electrode, and a light-emitting layer disposed between the transparent electrode and the reflective electrode; a transparent layer disposed on a light-exiting side of the transparent electrode; and a light extraction structure disposed on a light-exiting side of the transparent layer and having a protruding shape with inclined portions that are gradually narrowing from the transparent layer side, wherein the transparent layer and the light extraction structure have a larger refractive index than the light-emitting layer, and wherein the inclined portions of the light extraction structure are designed so as to satisfy at least one of Condition 1 and Condition 2 for extracting guided wave light emitted from the light-emitting layer and incident on the light extraction structure from the light extraction structure to the outside of the organic EL element, in a cross section taken along a plane perpendicular to the reflective electrode, where two inclination angles φ 1 and φ 2 formed between the reflective electrode and the inclined portions are the largest, wherein Condition 1 is given by sin - 1 ⁡ ( n 0 n 1 ) ≤ θ 1 ≤ 90 ⁢ ° , ⁢ n 1 ⁢ sin ⁢ ⁢ θ 1 = n 2 ⁢ ⁢ sin ⁢ ⁢ θ 2 , ⁢ sin ⁡ ( θ 2 + ϕ 1 ) ≥ n 0 n 2 , ⁢ sin ⁡ ( 180 ⁢ ° ⁢ - θ 2 - 2 ⁢ ⁢ ϕ 1 - ϕ 2 ) ≥ n 0 n 2 , ⁢ - n 0 n 2 < sin ⁡ ( 180 ⁢ ° - θ 2 - 2 ⁢ ⁢ ϕ 1 - 3 ⁢ ⁢ ϕ 2 ) < n 0 n 2 , and sin - 1 ⁡ ( n 2 n 0 ⁢ sin ⁡ ( 180 ⁢ ° - θ 2 - 2 ⁢ ⁢ ϕ 1 - 3 ⁢ ϕ 2 ) ) + ϕ 2 = 0 , and Condition 2 is given by sin - 1 ⁡ ( n 0 n 1 ) ≤ θ 3 ≤ 90 ⁢ ° , ⁢ n 1 ⁢ sin ⁢ ⁢ θ 3 = n 2 ⁢ ⁢ sin ⁢ ⁢ θ 4 , ⁢ sin ⁡ ( θ 4 - ϕ 2 ) ≥ n 0 n 2 , ⁢ - n 0 n 2 < sin ⁡ ( θ 4 - 3 ⁢ ⁢ ϕ 2 ) < n 0 n 2 , and sin - 1 ⁡ ( n 2 n 0 ⁢ sin ⁡ ( θ 4 - 3 ⁢ ϕ 2 ) ) + ϕ 2 = 0 , wherein n 0 denotes the refractive index of the outer area of the organic EL element, n 1 denotes the refractive index of the light-emitting layer, n 2 denotes the refractive index of the light extraction structure, θ 1 and θ 3 denote the angles formed between the guided wave light and the normal to the reflective electrode in the light-emitting layer, and θ 2 and θ 4 denote the angles formed between the guided wave light and the normal to the reflective electrode in the light extraction structure.