Results obtained from modeling the light out-coupling efficiency of an organic light-emitting diode (OLED) structure containing the recently developed first-generation fac-tris(2-phenylpyridine) iridium-cored dendrimer (Ir-G1) as the emissive organic layer are reported. Comparison of the results obtained for this material with those of corresponding structures based upon small-molecule and polymer emissive materials is made. The calculations of out-coupling efficiency performed here take account of many factors, including the photoluminescence quantum yield (PLQY) of the emissive materials. Further, how each material system might perform with regard to out-coupling efficiency when a range of possible PLQYs are considered is shown. The calculations show that the very high efficiency of dendrimer-based OLEDs can be attributed primarily to their high PLQY.