To obtain the maximum luminous efficiency from an organic material, it is necessary to harness both the spin-symmetric and anti-symmetric molecular excitations (bound electron–hole pairs, or excitons) that result from electrical pumping. Here, we demonstrate that this deficiency can be overcome by using a phosphorescent sensitizer to excite a fluorescent dye. The photoluminescence and sensitization effect between tris (2-phenylpyridine) iridium (Ir (ppy) 3) and 5,6,11,12-tetraphenylnaphthacene (rubrene) in the host of 4,4'-N,N-dicarbazole-biphenyl (CBP) were investigated. The energy transfer characteristics in the electroluminescent process of the system of CBP, Ir (ppy) 3 and Rubrene has been discuss in this article. The Ir (ppy) 3 sensitizer affords an effective way to improve the device performance. In the organic light-emitting diodes based on the Ir (ppy) 3, rubrene and CBP system, both the singlet and triplet excitons can be used.