The present invention relates to organic electroluminescent devices comprising a light-emitting layer B comprising a triplet-triplet annihilation (TTA) material, a thermally activated delayed fluorescence (TADF) material and a near-range-charge-transfer (NRCT) emitter material, which exhibits a narrow—expressed by a small full width at half maximum (FWHM)—emission. Further, the present invention relates to a method for obtaining a desired light spectrum and achieving suitable (long) lifespans of an organic electroluminescent device according to the present invention.