Injection, transport, absorption and phosphorescence properties of a series of blue-emitting In (III) emitters in OLEDs: A DFT and time-dependent dft study

Quantum-chemistry methods were explored to investigate the electronic structures, injection and transport properties, absorption and phosphorescence mechanism of a series of blue-emitting Ir(III) complexes {[(F ₂-ppy)₂ir(pta - X/pyN4)], where F2-ppy = (2,4-difluoro)phenylpyridine; pta = pyridine-1,2,4-triazole; X = phenyl(1); p-tolyl (2); 2,6-difluororophenyl (3); - CF₃ (4), and pyN4 = pyridine-1,2,4-tetrazolate (5)}, which are used as emitters in organic light-emitting diodes (OLEDs). The mobility of hole and electron were studied computationally based on the Marcus theory. Calculations of lonization potentials (IPs) and electron affinities (EAs) were used to evaluate the injection abilities of holes and electrons into these complexes. The reasons for the lower EL efficiency and phosphorescence quantum yields in 3-5 than in 1 and 2 have been investigated. These new structure-property relationships can guide an improved design and optimization of OLED devices based on blue-emitting phosphorescent Ir(III) complexes.