| abstract |
Disclosed is a highly reliable organic electroluminescent element, in particular a phosphorescent organic EL element using a low-molecular-weight host material, wherein the balance between electron and hole injection and an efficient phosphorescent mechanism are maintained. The organic electroluminescent element comprises a light-emitting layer between a positive electrode layer and a negative electrode layer, and the light-emitting layer contains a phosphorescent dopant material and a host material that has a molecular weight of not more than 10,000. The host material is composed of a first host material and a second host material that is different from the first host material. The difference of ionization potential (IP) between the first host material and the second host material is not more than 0.1 eV, the difference of electron affinity (EA) between the first host material and the second host material is not more than 0.1 eV, and the difference of triplet energy (T1) between the first host material and the second host material is not more than 0.1 eV. |