Organic electroluminescence device

Abstract

An organic EL device includes a pair of electrodes and an organic compound layer between pair of electrodes. The organic compound layer includes an emitting layer including a first material and a second material. The second material is a fluorescent material. Singlet energy EgS(H) of the first material and singlet energy EgS(D) of the second material satisfy a relationship of the following formula (1). The first material satisfies a relationship of the following formula (2) in terms of a difference ΔST(H) between the singlet energy EgS(H) and an energy gap Eg 77K (H) at 77K. EgS ( H )> EgS ( D )  (1) Δ ST ( H )= EgS ( H )− Eg 77K ( H )<0.3 (eV)  (2)

What is claimed is: 
     
         1 . An organic electroluminescence device, comprising:
 a pair of electrodes; and   an organic compound layer interposed between the pair of electrodes, the organic compound layer comprising an emitting layer comprising a first material and a second material,   wherein:   the first material is represented by a formula (101):   
       
         
           
           
               
               
           
         
         the second material is a fluorescent material; 
         rings A, B, and C each are a substituted or unsubstituted five- to seven-membered ring comprising as a ring-forming atom an atom selected from the group consisting of a carbon atom, a nitrogen atom, an oxygen atom, a sulfur atom, and a silicon atom; 
         the ring A is fused with the ring B and the ring C is fused with the ring B; 
         the ring C is optionally fused with an additional ring; 
         Q represents a group represented by a formula (103): 
       
       
         
           
           
               
               
           
         
         k is 1 or 2; 
         at least one of Y 1  to Y 6  is a carbon atom to be bonded to L; 
         one to three of Y 1  to Y 6  are a nitrogen atom(s); 
         the rest of Y 1  to Y 6  of the carbon atom bonded with L or the nitrogen atom is CAr 1 ; 
         Ar 1  is a substituted or unsubstituted aromatic hydrocarbon group; 
         when a plurality of CAr 1  are present, Ar 1  is mutually the same or different; and 
         L represents a single bond or a linking group. 
       
     
     
         2 . The organic electroluminescence device according to  claim 1 , wherein
 a half bandwidth of a photoluminescence spectrum of the first material is 50 nm or more.   
     
     
         3 . The organic electroluminescence device according to  claim 1 , wherein
 a half bandwidth of a photoluminescence spectrum of the first material is 75 nm or more.   
     
     
         4 . The organic electroluminescence device according to  claim 1 , wherein
 a difference ΔT between an energy gap Eg 77K (H) at 77K of the first material and an energy gap Eg 77K (D) at 77K of the second material satisfies a relationship of a formula (3) below,
   Δ T=Eg   77K ( H )− Eg   77K ( D )≥0.6 (eV)  (3).