Organic electroluminescent element

摘要

An organic electroluminescent element having a structure in which a plurality of light-emitting layers stacked between a first electrode with light reflectivity and a second electrode with optical transparency while one or more interlayers with a light transmissive property are interposed between the plurality of light-emitting layers. A first interlayer is formed as the interlayer closest to the first electrode. A first light-emitting unit is formed between the first electrode and the first interlayer to include a first light-emitting layer which has a first light-emitting source, and a second light-emitting unit is formed on a side of the first interlayer close to the second electrode to include a second light-emitting layer which has a second light-emitting source. The first interlayer is a semi-transmissive layer which has both of optical transparency and light reflectivity and has a total light absorption ratio of 10% or less.

主权项

1. An organic electroluminescent element with a structure in which a plurality of light-emitting layers are stacked between a first electrode with light reflectivity and a second electrode with optical transparency while one or more interlayers with a light transmissive property are interposed between the plurality of light-emitting layers,
wherein: the one or more interlayers includes a first interlayer closest to the first electrode; a first light-emitting unit is formed between the first electrode and the first interlayer to include a first light-emitting layer which is one of the plurality of light-emitting layers and has a first light-emitting source; a second light-emitting unit is formed on a side of the first interlayer close to the second electrode to include a second light-emitting layer which is one of the plurality of light-emitting layers and has a second light-emitting source; and the first interlayer is a semi-transmissive layer which has both of optical transparency and light reflectivity and has a total light absorption ratio of 10% or less, wherein the organic electroluminescent element has a characteristic which satisfies relations of:
0.9*X≦D1(λ1)≦1.1*X; 0.1*Y≦D3(λ2)≦2.0*Y; and 0.8*Z≦D1(λ1)+D2(λ1)≦1.2*Z, wherein: λ1 represents a weighted-averaged emission wavelength of the first light-emitting source; λ2 represents a weighted-averaged emission wavelength of the second light-emitting source; D1(λ1) represents an optical path length defined as a product of a refractive index at the wavelength λ1 and a thickness with regard to a medium situated between the first light-emitting source and the first electrode; D2(λ1) represents an optical path length defined as a product of a refractive index at the wavelength λ1 and a thickness with regard to a medium situated between the first light-emitting source and the semi-transmissive layer; D3(λ2) represents an optical path length defined as a product of a refractive index at the wavelength λ2 and a thickness with regard to a medium situated between the second light-emitting source and the semi-transmissive layer; and X, Y, and Z satisfy equations of X=φ1(λ1)*(λ1/4π)+λ1*l/2, Y=(φ2(λ2)*(λ2/4π)+λ2*m/2, and Z=φ1(λ1)+φ2(λ1)*(λ1/4π)+λ1*n/2, respectively, wherein: l, m, and n are integers of 0 or more, respectively; φ1 represents a phase shift expressed by a following formula (1) which occurs at the first electrode; φ2 represents a phase shift expressed by the following formula (1) which occurs at the semi-transmissive layer; φ1(λ1) represents a phase shift of light emitted from the first light-emitting source which arises from reflection at the first electrode; φ2(λ1) represents a phase shift of light emitted from the first light-emitting source which arises from reflection at the semi-transmissive layer; φ2(λ2) represents a phase shift of light emitted from the second light-emitting source which arises from reflection at the semi-transmissive layer; and the formula (1) is:φ=tan-1⁢{2⁢(n1⁢k2-n2⁢k1)n12-n22+k12-k22},(1) wherein: n1 and k1 representing a refractive index and an extinction coefficient of a layer in contact with a reflection layer, respectively; n2 and k2 representing a refractive index and an extinction coefficient of the reflection layer, respectively; and n1, n2, k1, and k2 are functions of λ.