No Access Submitted: 04 April 2008 Accepted: 19 July 2008 Published Online: 02 September 2008
Appl. Phys. Lett. 93, 093301 (2008);
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  • J. Mezyk
  • F. Meinardi
  • R. Tubino
  • M. Cocchi
We have investigated the mechanism of exciton dissociation in organometallic phosphorescent emitters by measuring the electric field-dependent time-resolved photoluminescence for thin vacuum-evaporated films of a model compound—tris(2-phenylpyridine) iridium (III) [Ir(ppy)3]. We have shown that the dissociation occurs from higher lying spin-mixed states before their relaxation to the lowest emissive levels, the lifetime of the latter not being significantly affected by external electric field. Knowledge about the mechanism of exciton dissociation in this class of materials is relevant for theoretical simulations of exciton kinetics in phosphorescent diodes as well as for optimization of the performances of these devices.
This work was supported by funds from the Italian MURST (FIRB Project RBNE03S7XZ “SYNERGY”) and the CARIPLO foundation. The contribution from Dr. M. Cocchi was supported by funds of CNR Project No. PM-P04-010 (MACOL).
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