Temperature-sensitive phosphorescene decay time and temperature-independent PL intensity of fac tris(2-phenylpyridine) iridium (Ir(PPY)(3)) have been observed in thin sold films of Ir(PPY)(3) doped in exothermic hosts tetrahydrofuran (THF), 4,4'-N,N'-dicarbazole-biphenyl (CBP) and polycarbonate (PC). We calculate these temperature dependences using a three-level model of three zero-field splitting substates for the lowest-energy triplet state with relaxation process among these substates, and we obtain good agreement with the experimental results. The theory is also successfully applied to the case of Ir(ppy)(3) doped in endothermic host such as N,N'-bis (3-methylphenyl)-N,N'-bis(phenyl)-benzidine (TPD). From the present model we understand the electronic processes in the photo-excited Ir(ppy)(3),