A study on the preparation and photophysical properties of an iridium(iii) complexed homopolymer

We have prepared a poly(styrene) [poly(Irppy2acac)] that has a bis(2-phenylpyridyl)iridium(III) acetylacetonate complex attached to every ‘monomer’ via a methylene unit. The polymer is solution processable and can be spin-coated to give good quality neat thin films. We show that despite the close proximity of the phosphorescent chromophores along the polymer backbone there is only a modest reduction in the solution photoluminescence quantum yield (PLQY) relative to a monomer model compound. The PLQY of the 4-ethylbenzyl substituted bis(2-phenylpyridyl)iridium(III) acetylacetonate complex was 52% while the poly(Irppy2acac) had a PLQY of 34%. Time-resolved photoluminescence measurements showed that the photoluminescence decay of the poly(Irppy2acac) in solution was bi-exponential indicating the presence of more than one emissive species, which was attributed to intra-polymer chromophore interactions. In contrast to the solution measurements the solid-state PLQY was very low (