Efficiency roll-off in TADF OLEDs: don’t just maximise the RISC

Le Zhang; Stefan Diesing; Arvydas Ruseckas; Ifor D. W. Samuel

doi:10.1117/12.2668433

8 June 2023 Efficiency roll-off in TADF OLEDs: don’t just maximise the RISC

Le Zhang, Stefan Diesing, Arvydas Ruseckas, Ifor D. W. Samuel

Proceedings Volume PC12584, Smart Materials for Opto-Electronic Applications; PC1258403 (2023) https://doi.org/10.1117/12.2668433
Event: SPIE Optics + Optoelectronics, 2023, Prague, Czech Republic

Abstract

Organic light-emitting diodes (OLEDs) are widely used for displays and promising for applications lighting, sensing and medicine. Thermally assisted delayed fluorescence (TADF) is an attractive way of harvesting triplets, without the need for heavy metals such as iridium. However, many TADF materials suffer severe efficiency roll-off i.e. as the light output of the device increases, the efficiency decreases. We will show how efficiency roll-off compares between phosphorescent, fluorescent and TADF OLED materials. The TADF literature suggests that efficiency roll-off should be addressed by increasing the rate of reverse intersystem crossing. We show this incomplete and propose an improved approach. Furthermore we introduce a measurement using variable repetition rate to measure key photophysical parameters to understand efficiency roll-off. Our results and analysis suggest how the serious problem of efficiency roll-off in TADF materials can be reduced.

Conference Presentation

Citation Download Citation

Le Zhang, Stefan Diesing, Arvydas Ruseckas, and Ifor D. W. Samuel "Efficiency roll-off in TADF OLEDs: don’t just maximise the RISC", Proc. SPIE PC12584, Smart Materials for Opto-Electronic Applications, PC1258403 (8 June 2023); https://doi.org/10.1117/12.2668433

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