Investigation into characteristics of blue iridium (III) pyrimidine complexes with suppressed shoulder peak emission

Abstract

Three novel blue-emitting iridium (III) complexes (Ir1, Ir2 and Ir3), embedding pyrimidine group have been synthesized. Density functional theory (DFT) calculations demonstrate that pyrimidine complex series occupy less component of triplet ligand centered (³LC) could restrain the vibronic shoulders comparing to the pyridine series. As for Ir1, the relative intensity of shoulder in electroluminescence (EL) spectrum is ∼0.6 of the intensity for dominate peak, relevant full width at half maximum (FWHM) is merely 47 nm. Such parameter gradually zooms out from trifluoro-to monofluoro-substitution in EL spectra. Furthermore, three complexes could obtain efficient EL performance, in which, devices based on Ir3 achieve the peak external quantum efficiency (EQE) of 28.9 %. In addition, the photoelectric properties of the three complexes display a certain regularity and this work indeed provides a strategy to modulate shoulder peak emission for blue phosphorescence.