Near-UV to red-emitting charged bis-cyclometallated iridium(III) complexes for light-emitting electrochemical cells.
Herein we report a series of charged iridium complexes emitting from near-UV to red using carbene-based N^C: ancillary ligands. Synthesis, photophysical and electrochemical properties of this series are described in detail together with X-ray crystal structures. Density Functional Theory calculations show that the emission originates from the cyclometallated main ligand, in contrast to commonly designed charged complexes using bidentate N^N ancillary ligands, where the emission originates from the ancillary N^N ligand. The radiative process of this series of compounds is characterized by relatively low photoluminescence quantum yields in solution that is ascribed to non-radiative deactivation of the excited state by thermally accessible metal-centered states. Despite the poor photophysical properties of this series of complexes in solution, electroluminescent emission from the bluish-green to orange region of the visible spectrum is obtained when they are used as active compounds in light-emitting electrochemical cells.
Laboratory of Photonics and Interfaces, Institute of Chemical Sciences and Engineering, Swiss Federal Institute of Technology, Station 6, CH-1015, Lausanne, Switzerland.
Florian
F
Kessler
Rubén D
RD
Costa
Davide
D
Di Censo
Rosario
R
Scopelliti
Enrique
E
Ortí
Henk J
HJ
Bolink
Sebastian
S
Meier
Wiebke
W
Sarfert
Michael
M
Grätzel
Md Khaja
MK
Nazeeruddin
Etienne
E
Baranoff