Patent ID: 7645523

Claim:
An organic electroluminescence element comprising: an anode; a hole transport layer; a light emitting layer made of organic compounds; an electron transport layer; and a cathode which are layered in order, wherein the light emitting layer and the electron transport layer are in direct contact with each other without any hole blocking layer provided between the light emitting layer and the electron transport layer, wherein said light emitting layer comprises an organic host material having an electron transport capability and an organic guest material of phosphorescent material; wherein an ionization potential energy of said organic host material is higher than that of said hole transport layer; wherein the difference in the ionization potential energy between said organic host material of said light emitting layer and said hole transport layer is in a range from 0.4 eV to 0.8 eV; and wherein said organic host material comprises an aluminum chelate complex represented by a general formula (A) wherein R2 denotes an alkyl, oxy, amino or hydrocarbon substituent having at least 1 carbon atom, with a carbon atom number being 1 to 10 in any one hydrocarbon moiety, R3 to R7 independently denote a hydrogen atom, alkyl, oxy, amino or hydrocarbon substituent having at least 1 carbon atom, with a carbon atom number being 1 to 10 in any one hydrocarbon moiety, R5, R6 and R7 are selected from the group consisting of cyano, halogen, and α-haloalkyl, α-haloalkoxy, amido, sulfonyl, carbonyl, carbonyloxy and oxycarbonyl substituents containing up to 10 carbon atoms, L denotes one of formulae (B) wherein R8 to R12 independently represent hydrogen or hydrocarbon groups of from 1 to 12 carbon atoms, with the proviso that R8 and R9 together or R9 and R10 together can form a fused benzo ring, R13 to R27 independently represent hydrogen or hydrocarbon groups of from 1 to 12 carbon atoms, with the proviso that R13 and R14 or R14 and R15 can form a fused benzo ring, R18 and R19 or R19 and R20 can form a fused benzo ring, and R23 and R24 or R24 and R25 can form a fused benzo ring, wherein said organic guest material of phosphorescent material is 2,3,7,8,12,13,17,18-octaethyl-21H, 23H-porphine platinum (II), wherein said aluminum chelate complex represented by the general formula (A) does not include formula 52,