To obtain a high efficiency flexible deep-red light source, phosphorescent organic light-emitting-diodes with the emitter of bis(10-hydroxy-benzo(h)quinolinato)beryllium [Bebq(2)] doubly doped with iridium(III)bis(2-phenylquinoline-N,C2')acetylacetonate [(pq)(2)Ir(acac)] and RP411 (proprietary red phosphorescent dye) have been fabricated on the polyethylene-2,6-dicarboxylnaph-thalate (PEN) substrates. The device doubly doped with (pq) Ir-2(acac) and RP411 in the emitter showed the maximum current efficiency of 22.4 cd/A with current efficiency improvement of 10% under a luminance of 10,000 cd/m(2) compared to that of the device singly doped with RP411. In this device, luminance and current efficiency were found to be 12000 cd/m(2) at an applied voltage of 8 V and 17.3 cd/A under a luminance of 10,000 cd/m(2), respectively. The peak wavelength in the electroluminescent spectral distribution and color coordinates on the Commission Internationale de I'Eclairage (CIE) chart were 623 nm and (0.66, 0.34), respectively.