The utilization of molecular phosphorescent dyes in polymer-based organic light emitting diodes (OLEDs) was investigated by codoping several phosphorescent dopants into poly(N-vinylcarbazole) (PVK)-based single layer light emitting diodes (LEDs). In particular, green fac-tris(2-phenylpyridine)iridium(III), [Ir(ppy)3], red tris(4,7-diphenyl-1,10-phenanthroline)rhenium dications, [Ru(4,7-Ph2-phen)3]2+, and (2,3,7,8,12,13,17,18-octaethyl-21H,23H-porphyrin)platinum(II) (PtOEP) were used. In the phosphorescence dye doubly doped PVK system ca. x wt % [Ru(4,7-Ph2-phen)3]2+:1wt % Ir(ppy)3:PVK(x) 0.5-5), the intensity ratio (Ri) of red emission vs green emission as a function of doping ratio (Rc) of [Ru(4,7-Ph2-phen)3]2+ vs Ir(ppy)3 is found according to a power-law function with the exponent of 2.0 (0.2 for photoluminescence, which obey the power law with Ri