Iridium complex, method for producing iridium complex, organic electroluminescent element, display device, and lighting device
Disclosed herein are an iridium complex having improved luminous efficiency and emission lifetime, a method for producing the same, an organic electroluminescent element using the iridium complex, and a display device and a lighting device that include the organic electroluminescent element. The iridium complex is contained in at least one organic layer sandwiched between an anode and a cathode of an organic electroluminescent element, and has a coefficient of external influence of 0.73 Å 2 /MW or less as defined by the following definition equation: Coefficient of external influence (Svdw)=Van der Waals surface area [Å 2 ]/molecular weight (MW).
1. An iridium complex having a coefficient of external influence of 0.73 Å 2 /MW or less as defined by the following definition equation:
Coefficient of external influence (Svdw)=Van der Waals surface area [Å 2 ]/molecular weight (MW),
wherein the iridium complex has a partial structure represented by formula (N):
wherein R is selected from the group consisting of
2. A method for producing the iridium complex according to claim 1 , comprising synthesizing the iridium complex by a solvent-free reaction using, as an alternative to a reaction solvent, an organic compound serving as a ligand of the iridium complex.
3. The method for producing the iridium complex according to claim 2 , wherein a 6-coordinated iridium complex is formed by coordination of ligands to iridium, and then a substituent group is introduced into the ligands of the iridium complex.
4. Ah organic electroluminescent element comprising the iridium complex according to claim 1 .
5. A display device comprising the organic electroluminescent element according to claim 4 .
6. A lighting device comprising the organic electroluminescent element according to claim 4 .