Open Access

Manuel Engelmayer

• Abstract: A photoluminescence measurement setup was constructed to investigate on the optical emitter properties of thin film light-emitting diodes during electrical operation. Firstly, investigations - with this setup - on organic LEDs containing either phosphorescent Ir-based molecules or TADF based emitters were compared. Furthermore, the influence of polar materials used in adjacent charge transport layers was studied. The introduction of a sizeable Giant Surface Potential lead to a significant amount of Photoluminescence Quantum Efficiency reduction already prior to the electroluminescent turn-on of the LED. Secondly, the performance of Quantum-Dot-LEDs (QDLEDs) based on InP/ZnSe/ZnS Core-Shell-Shell structures was investigated under electrical bias. While a considerable amount of field induced efficiency losses was observed in the reverse bias regime, a developed theoretical model clearly identified Auger quenching as the dominant loss process under forward operation. ObservedAbstract: A photoluminescence measurement setup was constructed to investigate on the optical emitter properties of thin film light-emitting diodes during electrical operation. Firstly, investigations - with this setup - on organic LEDs containing either phosphorescent Ir-based molecules or TADF based emitters were compared. Furthermore, the influence of polar materials used in adjacent charge transport layers was studied. The introduction of a sizeable Giant Surface Potential lead to a significant amount of Photoluminescence Quantum Efficiency reduction already prior to the electroluminescent turn-on of the LED. Secondly, the performance of Quantum-Dot-LEDs (QDLEDs) based on InP/ZnSe/ZnS Core-Shell-Shell structures was investigated under electrical bias. While a considerable amount of field induced efficiency losses was observed in the reverse bias regime, a developed theoretical model clearly identified Auger quenching as the dominant loss process under forward operation. Observed metastabilities in these QD-based systems show the need for further research in this field, as a model to explain these effects could be proposed to be linked to ion migration in the QD- and adjacent charge transport layers, however definitive proof is still missing.…