Organic electroluminescent device

An organic electroluminescent device comprising at least one organic compound layer, of which at least one is an organic blue-emitting layer, as sandwiched between a pair of electrodes, wherein (1) the organic blue-emitting layer comprises an organic host compound having a fluorescence quantum efficiency of not smaller than 0.3 in a solid state and a fluorescent substance, and the organic host compound and the fluorescent substance are selected such that the device retains a monomeric blue-emitting ability and the fluorescent substance has an energy gap that is smaller than the energy gap of the organic host substance, and (2) all the organic compound layers have a glass transition temperature of not lower than 75° C., while the organic compound layers adjacent to the organic blue-emitting layer, when present, have a glass transition temperature of not lower than 105° C., wherein the organic host compound and the fluorescent substance are selected such that both interaction (3) between the organic host compound and the fluorescent substance and (4) between the organic host compound and any adjacent compound layer, are absent whereby said device retains said monomeric blue-emitting ability.