Abstract
Luminescent materials, which consist of organo-transition-metal compounds, are attractive for optimizations of organic light emitting diodes (OLEDs). This is a consequence of significantly higher efficiencies obtainable with these compounds as compared to organic emitters. In this contribution a basic model is presented, how electron-hole recombination, i.e. the exciton formation process, can be ...
Abstract
Luminescent materials, which consist of organo-transition-metal compounds, are attractive for optimizations of organic light emitting diodes (OLEDs). This is a consequence of significantly higher efficiencies obtainable with these compounds as compared to organic emitters. In this contribution a basic model is presented, how electron-hole recombination, i.e. the exciton formation process, can be visualized and how the singlet and triplet states of the (doped) luminescent compounds are populated. This takes place by specific singlet and triplet paths which involve dopant-to-matrix charge transfer states. It is also explained, why the excitation energy is harvested in the lowest triplet state of these complexes. In principle, one can obtain a four times higher efficiency than with (small) organic singlet emitter molecules. Electron-hole recombination should preferentially occur on the triplet emitter itself, rather than on matrix molecules with subsequent energy transfer to the luminescent center.
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