Optoelectronic properties of OLEC devices based on phenylquinoline and phenylpyridine ionic iridium complexes

Abstract

Ionic transition metal complexes (iTMCs) have already been demonstrated to be a promising type of material to fabricate low-cost light sources, which are much more competitive in terms of realization costs with respect to standard organic light emitting diodes. The device performance, optical and morphological properties of thin films of two different complexes [Ir(phenylpyridine)₂(5-Me-1,10-phen)][PF₆] and [Ir(phenylquinoline)₂(5-Me-1,10-phen)][PF₆] have been measured and compared. The use of an ionic liquid as part of the processing procedure shows advantages in terms of low operation voltage, which is as low as 3.5 Volts. However, it leads to drawbacks in terms of device lifetime, limited to t_1/2 = 2 min, and maximum achievable brightness (1425 cd m⁻²vs. 3040 cd m⁻² without ionic liquid, for the complex [Ir(phenylpyridine)₂(5-Me-1,10-phen)][PF₆]).