Polymer phosphorescence device using a new green emitting ir(iii) complex

Abstract

We have synthesized a new green Ir(III) complex fac-tris-(3-methyl-2-phenyl pyridine)iridium(III) Ir(mpp) 3 and fabricated phosphorescent polymer light-emitting device using it as a triplet emissive dopant in PVK. Ir(mpp) 3 showed absorption centered at 388 nm corresponding to the 1 MLCT transition as evidenced by its extinction coefficient of the order of 10 3 . From the PL and EL spectra of the Ir(mpp) 3 doped PVK film, the emission maximum was observed at 523 nm, due to the radiative decay from the 3 MLCT state to the ground state, confirming a complete energy transfer from PVK to Ir(mpp) 3 . The methyl substitution has probably caused a red shift in the absorption and emission spectrum compared to Ir(ppy) 3. The device consisting of a 2 % doped PVK furnished 4.5 % external quantum efficiency at 72 cd/m 2 (current density of 0.45 mA/cm 2 and drive voltage of 13.9 V) and a peak luminance of 25,000 cd/m 2 at 23.4 V (494 mA/cm 2 ). This work demonstrates the impact of the presence of a methyl substituent at the 3-position of the pyridyl ring of 2-phenylpyridine on the photophysical and electroluminescence properties.? 2002 Taylor & Francis Group, LLC.