Photoluminescence properties of facial- and meridional-Ir(ppy)3 thin films

Photoluminescence (PL) properties of tris(2-phenylpyridine) iridium [Ir(ppy)3] thin films which contain both facial- and meridional-Ir(ppy)3 have been investigated. It is found that the thin films show red-shifted and broader PL spectra in comparison with those of the facial-Ir(ppy)3 [fac-Ir(ppy)3] thin films. PL quantum efficiency of the meridional-Ir(ppy)3 [mer-Ir(ppy)3] doped 4,4′-N,N′-dicarbazole-biphenyl (CBP) thin films is estimated to be 30% from PL spectra and PL quantum efficiencies of Ir(ppy)3 [the mixture of fac-Ir(ppy)3 and mer-Ir(ppy)3] doped CBP thin films. The PL quantum efficiency is much lower than that of fac-Ir(ppy)3 doped CBP thin films.