Blue and blue–green PhOLEDs prepared with neutral heteroleptic iridium(III) complexes comprising substituted pyridine-1,2,4-triazoles as the ancillary ligands

• Two neutral heteroleptic iridium(III) complexes have been investigated.
• Sky-blue and blue-green devices were obtained with the two complexes.
• UV–visible absorption and photoluminescence spectroscopy of the two complexes were investigated.
• High brightness and current efficiency were obtained.

Two neutral heteroleptic iridium(III) complexes bearing substituted pyridine 1,2,4-triazoles as the ancillary ligands have been designed and investigated as emitters for PhOLEDs. Interestingly, blue and blue–green devices were obtained with the two complexes. Best devices were obtained with C1 and reached a maximum brightness of 10,200 cd/m2, a current efficiency of 4.3 cd/A at an operation voltage of 7.9 V while exhibiting the unusual low turn-on voltage of only 2.8 V. UV–visible absorption and photoluminescence spectroscopy as well as the cyclic voltammetry of the two iridium(III) complexes were also investigated.