An inconvenient influence of iridium(III) isomer on OLED efficiency.
The recently reported heteroleptic cyclometallated iridium(III) complex [Ir(2-phenylpyridine)(2)(2-carboxy-4-dimethylaminopyridine)] N984 and its isomer N984b have been studied more in detail. While photo- and electrochemical properties are very similar, DFT/TDDFT calculations show that the two isomers have different HOMO orbital characteristics. As a consequence, solution processed OLEDs made using a mixture of N984 and isomer N984b similar to vacuum processed devices show that the isomer has a dramatic detrimental effect on the performances of the device. In addition, commonly used thermogravimetric analysis is not suitable for showing the isomerization process. The isomer could impact performances of vacuum processed OLEDs using heteroleptic cyclometallated iridium(III) complexes as dopant.
Baranoff
Etienne
E
Laboratory of Photonics and Interfaces, Institute of Chemical Sciences and Engineering, School of Basic Sciences, Swiss Federal Institute of Technology, Station 6, CH-1015, Lausanne, Switzerland. etienne.baranoff@epfl.ch
Bolink
Henk J
HJ
De Angelis
Filippo
F
Fantacci
Simona
S
Di Censo
Davide
D
Djellab
Karim
K
Grätzel
Michael
M
Nazeeruddin
Md Khaja
MK
D004563:Electrochemistry; D007495:Iridium / Q000737:chemistry*; D007536:Isomerism; D008027:Light; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000737:chemistry*; D011789:Quantum Theory
D009942:Organometallic Compounds; D007495:Iridium