This invention has an objective to improve durability at elevated temperature in organic electroluminescent devices using coumarin derivatives as dopant in a luminescent layer. This invention attains the above objective by providing in the organic electroluminescent devices formed by laminating an anode, a hole injection layer, a hole transportation layer, a luminescent layer, an electron transportation layer and a cathode in this order, the luminescent layer which comprises as dopant the green light-emitting coumarin derivative and hole- and electron-transporting substances as host; said coumarin derivative consisting of a plurality of coumarin groups bound to an aromatic ring, heterocycle, or any combination thereof, and exhibiting a glass transition point of 150.degree. C. or higher or a melting point of 297.degree. C. or higher.