High efficiency and stable-yellow phosphorescence from OLEDs with a novel fluorinated heteroleptic iridium complex

• A novel Ir–bt type complex with multi-fluorine functionalization was synthesized.
• The complex exhibited high quantum yield (0.56) and short lifetime (0.37 μs).
• Influence of fluorine atoms on photophysical properties of the complex was investigated.
• Highly efficient yellow OLEDs using the complex as emitter were fabricated.
• Stable yellow electrophosphorescence from the device was achieved.

The performance of a heteroleptic bis-cyclometalated iridium complex based on 2-(2,3,4-trifluorophenyl)benzo[d]thiazole [(tfbt)2Ir(acac)] was investigated as a new phosphorescent emitter in OLEDs. The devices showed very high efficiency at various dopant concentrations and maximum efficiency was achieved at 6 wt% dopant concentration. A comparison of the performances of phosphorescent OLEDs with the new emitter versus those with prototype-based (bt)2Ir(acac) emitter revealed a remarkable improvement of efficiency at all dopant concentrations. These preliminary results obtained with the tfbt-based emitter indicate that this family of cyclometalated ligands with multi-fluorine functionalization is a promising compound for the development of highly emissive complexes.

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