A Non‐Doped Phosphorescent Organic Light‐Emitting Device with Above 31% External Quantum Efficiency

Abstract

The demonstrated square-planar Pt(II)-complex has reduced triplet-triplet quenching and therefore a near unity quantum yield in the neat thin film. A non-doped phosphorescent organic light-emitting diode (PhOLED) based on this emitter achieves (31.1 ± 0.1)% external quantum efficiency without any out-coupling, which shows that a non-doped PhOLED can be comparable in efficiency to the best doped devices with very complicated device structures.

Kinetic Monte Carlo study of triplet-triplet annihilation in organic phosphorescent emitters

“…13). A similar analysis was recently presented by Zhang and Forrest, 14 who studied three archetypal phosphorescent organic light emitters based on Ir or Pt dye-complexes, including Ir(ppy) 3 in a 4; 4 0 -N; N 0 -dicarbazole-biphenyl (CBP) host. From a study of the concentration dependence in the 2-16 vol.…”

“…Namdas et al 12 and Ribiere et al 13 adopted this point of view, and deduced from transient PL studies for a series of dendrimers with a tris(2-phenylpyridine)iridium (Ir(ppy) 3 ) core that the exciton hopping rate decreases exponentially with the hopping distance (R), consistent with an exchange (Dexter-type) interaction with a rate proportional to expðÀ2R=kÞ. For the two sets of materials studied, including in Ref.…”

“…Based on these simulation results, the novel method for determining the predominant mechanism from the PL decay, mentioned above, is described. A comparison is given with the experimental results for Ir(ppy) 3 -based materials studied in Ref. 14.…”

“…% range, the authors argued that analyses in terms of the single-step mechanism would give rise to unrealistically large dipoledipole interaction radii, and that Dexter-type triplet diffusion is rate-determining down to the smallest dye-concentration included. For the Ir(ppy) 3 -based systems, the concentration dependence of the TTA rate was argued to be consistent with an interaction decay length k ¼ 1.6 nm. Interestingly, this value of k is well outside the range of values deduced from experiment in Refs.…”

“…[1][2][3] In these materials, the spin-orbit interaction induced by the heavy-metal atoms gives rise to exciton states with a quantum-mechanically mixed singlet and triplet character. Due to fast intersystem crossing (ISC), singlet states are almost instantaneously converted to triplet states, so that virtually all emission is due to phosphorescence.…”