Patent ID: 7986091

Claim:
A diode comprising an organic electroluminescent layer inserted between a lower electrode and an upper electrode, and between a lower reflecting layer and an upper reflecting layer, forming between them a resonant optical cavity for a range of wavelengths of light rays that can be emitted by said electroluminescent layer, wherein λ CN is included in said range of wavelengths and is defined as the resonant wavelength of the light rays emitted by the electroluminescent layer in the normal direction within said resonant optical cavity, said normal direction being defined as being normal to said lower reflecting layer and to said upper reflecting layer, wherein at least one of the electrodes and the reflecting layer located on the same side as this electrode relative to said electroluminescent layer is transparent or semi-transparent to said emitted light rays, wherein said diode includes at least one light extractor comprising a light entry section, optically coupled to said electroluminescent layer via said electrode and said reflecting layer that are transparent or semi-transparent, a light exit section, which is oriented towards the outside of the diode and has a smaller area than that of the entry section, and reflecting side walls, which are bounded by said entry section and by said exit section, and wherein, in order to limit the range of wavelengths of light rays exiting said diode to an upper limit λ C-lim , i.e. in order to exclude a high proportion of the light rays emitted by the electroluminescent layer as far as their wavelength is out of an interval that is defined to be narrower than said range of wavelengths of light rays that can be emitted by the electroluminescent layer and that exit from the resonant optical cavity, the reflecting side walls of the at least one extractor have a suitable shape so that there is an angle called the cut-off angle θ lim defined by the equation cos θ lim /λ CN such that: the emitted light rays, which penetrate via its entry section at an angle of emission not exceeding said cut-off angle θ lim , emerge from this extractor via its exit section, said angle of emission being measured relative to said normal direction; and the emitted light rays, that penetrate via its entry section at an angle of emission greater than this cut-off angle θ lim , do not emerge from the extractor via its exit section, and wherein λ C-lim corresponds to the wavelength of the light rays that have an emission maximum at the emission angle equal to said cut-off angle θ lim .