We have observed the Raman spectrum of an operating phosphorescent organic light-emitting diode fabricated with bis(2-(2'-benzothienyl)-pyridinato-N, C-3') iridium( acetylacetonate) (Btp(2)Ir(acac)) as a phosphorescent emitter with excitation at 532 nm. All of the observed bands have been attributed to Btp(2)Ir( acac) because of the resonance Raman effect. We have determined the temperature of the emitting layer containing Btp(2)Ir( acac) from the ratio of the anti-Stokes to Stokes Raman bands of the 283-cm (1) vibrational mode attributed to Btp(2)Ir( acac). The temperature of the emitting layer is estimated to be 89 +/- 8 degrees C at a current density of 400 A/m(2). (C) 2010 Elsevier B.V. All rights reserved.