Patent ID: 8786177

Claim:
A single-photon type organic electroluminescent element comprising: a first electrode having optical transparency; a second electrode; and a plurality of light-emitting layers disposed between the first and second electrodes, wherein the plurality of light-emitting layers stacked between the first and second electrodes each emit light having a different peak wavelength, and each of the light-emitting layers is disposed separately from the second electrode at such a position that optical resonance is generated by reflected light emitted from a predetermined light-emitting layer toward the second electrode and reflected by the second electrode to return, and light emitting from the predetermined light-emitting layer toward the first electrode, wherein a distance between a light-emitting center portion of a k-th light-emitting layer, “k” representing a natural number, counted from a side of the first electrode among the plurality of light-emitting layers and a portion of the second electrode which reflects light falls within a range of 0.9 to 1.1 times a resonance distance d k represented by the following Equation (1): d k = m k . ⁢ λ k 4 ⁢ n [ Numerical ⁢ ⁢ Formula ⁢ ⁢ 1 ] wherein λ k represents a peak wavelength of light emitted from the k-th light-emitting layer, n represents an average refractive index of a member placed between the k-th light-emitting layer and the second electrode, and m k is a positive odd number.