Organic electroluminescent element

1. An organic electroluminescent element comprising:

at least a pair of electrodes,

at least one organic light-emitting layer between the pair of electrodes, and

at least one lens A on a light-extracting surface of the pair of electrodes,

wherein one of the pair of electrodes is a reflective electrode, and the other is a semi-transmissive/semi-reflective electrode, and

wherein a real part n 1 of a refractive index of the organic light-emitting layer and a real part n 2 of a refractive index of the lens A satisfy the relationship n 1 >n 2 , and the real part n 2 is represented by Expression (1) described below:

n 2 ≦n 3 sin θ 2   Expression (1)

in Expression (1), n 3 represents a real part of a refractive index of a lens B having a different refractive index from the lens A; n 3 and n 1 satisfy the relationship n 3 >n 1 ; and θ 2 represents the smallest angle at which when the lens A in the organic electroluminescent element is replaced by the lens B, a perpendicular line is drawn from the light extracting surface to the organic light-emitting layer, light emerged from the organic light-emitting layer passes through the lens B at an angle of θ 3 with respect to the perpendicular line, and a change in chromaticity (Δu′v′) between the angle of θ 3 and the case where θ 3 is equal to 0° on an u′v′ chromaticity coordinate is represented by Expression (2) described below, the change in chromaticity (Δu′v′) is 0.1 or less

Δ u′v′ =√{square root over (( u ′(θ 3 )− u ′(0)) 2 +( v ′(θ 3 )− v ′(0)) 2 )}{square root over (( u ′(θ 3 )− u ′(0)) 2 +( v ′(θ 3 )− v ′(0)) 2 )}{square root over (( u ′(θ 3 )− u ′(0)) 2 +( v ′(θ 3 )− v ′(0)) 2 )}{square root over (( u ′(θ 3 )− u ′(0)) 2 +( v ′(θ 3 )− v ′(0)) 2 )}.  Expression (2)

2. The organic electroluminescent element according to claim 1 , wherein the real part n 2 of the refractive index of the lens A satisfies Expression (3) described below:

n 3 sin θ 2 −0.1≦ n 2 ≦n 3 sin θ 2.   Expression (3)

3. The organic electroluminescent element according to claim 1 , wherein when a distance between the pair of electrodes is represented by “d”, a range of wavelengths about the peak intensity of light emitted from the organic light-emitting layer ±20 nm is represented by λ, and a phase shift of light reflected between the pair of electrodes is represented by φ, the distance d, the range of wavelengths λ and the phase shift φ satisfy Expression (4) described below and the relationship m≧2:

m

=

2

⁢

d

λ

+

ϕ

2

⁢

π

Expression

⁢

⁢

(

4

)

where “m” is an integer.

4. An organic electroluminescent element comprising:

at least a pair of electrodes,

at least one organic light-emitting layer between the pair of electrodes, and

at least one lens A on a light-extracting surface of the pair of electrodes,

wherein one of the pair of electrodes is a reflective electrode, and the other is a semi-transmissive/semi-reflective electrode, and

wherein a real part n 1 of a refractive index of the organic light-emitting layer and a real part n 2 of a refractive index of the lens A satisfy the relationship n 1 >n 2 , and the real part n 2 is represented by Expression (1)′ described below:

n 2 ≦n 3 sin θ 4   Expression (1)′

in Expression (1)′, n 3 represents a real part of a refractive index of a lens B having a different refractive index from the lens A; n 3 and n 1 satisfy the relationship n 3 >n 1 ; and θ 4 represents an angle obtained when the lens A in the organic electroluminescent element is replaced by the lens B, a perpendicular line is drawn from the light extracting surface to the organic light-emitting layer, light emerged from the organic light-emitting layer passes through the lens B at an angle of θ 3 with respect to the perpendicular line, a change in chromaticity (Δu′v′) between the angle of θ 3 and the case where θ 3 is equal to 0° on an u′v′ chromaticity coordinate is represented by Expression (2) described below, and an angle at which a differential value when the change in chromaticity (Δu′v′) is differentiated with respect to θ 3 d(Δu′v′)/dθ 3 is equal to zero is defined as θ B , and θ 4 has the same value as the change in chromaticity (Δu′v′) corresponding to θ B and has a large value next to θ B

Δ u′v ′=√{square root over (( u ′(θ 3 )− u ′(0)) 2 +( v ′(θ 3 )− v ′(0)) 2 )}{square root over (( u ′(θ 3 )− u ′(0)) 2 +( v ′(θ 3 )− v ′(0)) 2 )}{square root over (( u ′(θ 3 )− u ′(0)) 2 +( v ′(θ 3 )− v ′(0)) 2 )}{square root over (( u ′(θ 3 )− u ′(0)) 2 +( v ′(θ 3 )− v ′(0)) 2 )}.  Expression (2)

5. The organic electroluminescent element according to claim 4 , wherein the real part n 2 of the refractive index of the lens A satisfies Expression (3)′ described below:

n 3 sin θ 4 −0.1 ≦ n 2 ≦n 3 sin θ 4 .  Expression (3)′

6. The organic electroluminescent element according to claim 4 , wherein when a distance between the pair of electrodes is represented by “d”, a range of wavelengths about the peak intensity of light emitted from the organic light-emitting layer ±20 nm is represented λ, and a phase shift of light reflected between the pair of electrodes is represented by φ, the distance d, the range of wavelengths λ and the phase shift φ satisfy Expression (4) described below and the relationship m≧2:

m

=

2

⁢

d

λ

+

ϕ

2

⁢

π

Expression

⁢

⁢

(

4

)

in Expression (4), “m” is an integer.