Cationic iridium complex for the design of soft salt-based phosphorescent OLEDs and color-tunable light-emitting electrochemical cells

Phosphorescent Organic Light-Emitting Diodes (PhOLEDs) based on iridium (III) soft salt were designed and studied. Heteroleptic anionic iridium complex (A) was prepared with thiocyanate anions and cationic iridium complex (C) was synthesized with 4,4′-dinonyl-2,2′-byridine as the ancillary ligand. Electronic and spectroscopic properties of the resulting combination of soft salt C·A were investigated by mean of UV–visible absorption, fluorescence spectroscopy and cyclic voltammetry. DFT calculations were also performed and the electroluminescent performances evaluated. Light-emitting electrochemical cells (LECs) displaying color-variable emission were also obtained. This color tunability aroused from a modification of the molecular packing of the emissive layer with the temperature.

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► Phosphorescent OLEDs based on iridium (III) soft salt were designed and studied.
► LECs were also prepared with the cationic iridium complex as single emitter.
► Investigations of the electronic and spectroscopic properties of the ion-paired iridium complexes.
► Electroluminescent performances of both the OLEDs and the LECs.
► Color-variable emission from green to yellow was obtained for the LECs prepared with the cationic complex.