27 September 2013 Correlation between shift in recombination zone and efficiency roll-off in phosphorescent organic light emitting devices (PHOLEDs)
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Abstract
We study the correlation between the shift in recombination zone and the efficiency roll-off in typical PHOLEDs. To probe the shift in recombination zone, electroluminescence spectra of devices with various architectures at different current densities are studied. Results show that high efficiency at low current density mostly originates from the interfacial emission at the EML/ETL interface due to the formation of host excitons followed by the subsequent energy transfer to the guests. Furthermore, increase in the current density shifts the recombination zone from the EML/ETL interface towards the HTL/EML interface where the device emission is the result of direct charge trapping on the guest sites. The results suggest that the shift in recombination zone and subsequent change in emission mechanism play a main role on the efficiency roll-off.
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Hossein Zamani Siboni, Hossein Zamani Siboni, Hany Aziz, Hany Aziz, } "Correlation between shift in recombination zone and efficiency roll-off in phosphorescent organic light emitting devices (PHOLEDs)", Proc. SPIE 8829, Organic Light Emitting Materials and Devices XVII, 882929 (27 September 2013); doi: 10.1117/12.2023783; https://doi.org/10.1117/12.2023783
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