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. (c) 2005 Elsevier B.V. All rights reserved.