Chiral Iridium(III) Complexes in Light-Emitting Electrochemical Cells: Exploring the Impact of Stereochemistry on the Photophysical Properties and Device Performances

Despite
hundreds
of cationic bis-cyclometalated iridium­(III) complexes having been
explored as emitters for light-emitting electrochemical cells (LEECs),
uniformly their composition has been in the form of a racemic mixture
of Λ and Δ enantiomers. The investigation of LEECs using
enantiopure iridium­(III) emitters, however, remains unprecedented.
Herein, we report the preparation, the crystal structures, and the
optoelectronic properties of two families of cyclometalated iridium­(III)
complexes of the form of [(C^N)2Ir­(dtBubpy)]­PF6 (where dtBubpy is 4,4′-di-tert-butyl-2,2′-bipyridine)
in both their racemic and enantiopure configurations. LEEC devices
using Λ and Δ enantiomers as well as the racemic mixture
of both families have been prepared, and the device performances were
tested. Importantly, different solid-state photophysical properties
exist between enantiopure and racemic emitters, which are also reflected
in the device performances.