Researchers show that the performance of the TADF-based OLEDs can be significantly improved by heating

Researchers from the Kaunas University of Technology, the V. Lashkaryov Institute of Semiconductor Physics NAS of Ukraine, and Yuan Ze University, have shown that the performance of the TADF-based OLEDs can be significantly improved by heating, while extremely dependent on the applied biases. These findings are of interest, as normally high temperatures deteriorate the performance of light-emitting diodes, leading to excessive leakage currents, material degradation, and device failure. 

The researchers have achieved a 5 to 6 times improvement in OLED electroluminescence when operating near the turn-on voltage and heating to 50 °C, but also report that the enhancement decreases at higher applied biases. At the same time, current characteristics reveal normal and abnormal regions, where currents increase and decrease with temperature, respectively. 

The researchers say that the discrepancy of temperature dependence of electroluminescence and current in the abnormal region provides improved external quantum efficiency and power efficiency of the device upon heating. These findings open up potential opportunities for exploitation of TADF-based OLEDs as energy upconverters pumping waste heat to light emissions.