Influence of the bias-dependent emission zone on exciton quenching and OLED efficiency

We present an electro-optical model of a three-layer phosphorescent OLED which accurately describes the measured current efficiency and transient electroluminescence decay for different biases. Central findings are a bias-dependent emission zone, which influences light outcoupling as well as exciton quenching, and the presence of strong triplet-polaron quenching even at low bias. The measured current efficiency initially increases up to 9 V before it decreases, where the increase is found to be caused by reduced triplet-polaron quenching with holes, while the decrease is caused by a reduced light outcoupling and increased triplet-triplet annihilation. The numerical model allows identifying the individual contributions of the exciton continuity equation and explains the electroluminescence decay, which deviates significantly from a mono-exponential decay due to the dominating influence of exciton generation and quenching after the external bias is removed.


Publié dans:
Organic Electronics, 70, 219-226
Année
Jul 01 2019
ISSN:
1566-1199
1878-5530
Mots-clefs:
Laboratoires:




 Notice créée le 2019-06-18, modifiée le 2019-06-27

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