Enhancing efficiency roll-off in radical OLEDs by utilising a novel TADF:radical single-layer OLED approach (OPTICARE-OLED)

In the modern world, displays are essential components found in nearly all electronic devices, ranging from mobile phones to monitors and televisions. The disruptive organic light-emitting diode (OLED) technology has been instrumental in driving the widespread adoption of displays, offering advantages such as light weight, flexibility, and tunable properties enabled by the use of organic semiconductors. However, conventional organic emitters have certain limitations. To overcome these limitations and enhance OLED technology further, recent breakthroughs have identified radical emitters with unpaired valence electrons. These radical emitters show great promise in eliminating challenges associated with conventional organic emitters, paving the way for manufacturing of more efficient and sustainable OLED displays.

However, despite remarkable advances in radical OLEDs (ROLEDs), their full potential to revolutionise organic optoelectronics remains untapped. ROLEDs exhibit high peak efficiency but suffer from a severe 'roll-off' effect, where efficiency decreases with increasing current density, even at moderately high current densities. OPTICARE-OLED is an ambitious project that will follow a multidisciplinary approach to solve this problem using a novel device design consisting of a TADF:radical single-layer OLED (utilizing thermally activated delayed fluorescence (TADF) emitters as sensitizers and radicals as terminal emitters in a 'hyperfluorescent' architecture). Through a device engineering and simulation development based approach, with inputs from spectroscopic studies, predictive models will be built and used to design TADF:radical combinations and device architectures to optimize charge balance, charge trapping and injection-to-luminescence yield in ROLEDs. Taking this holistic approach, I believe will unlock solutions, previously unattainable, mitigating the roll-off effect and realising the full potential of ROLEDs in organic optoelectronics.