Leveraging specially-crafted organic molecules with a large singlet-triplet splitting, researchers from North Carolina State University demonstrated blue OLED chemistries capable of forming triplet excitons via direct charge injection.
Through subsequent triplet fusion, this allows the organic molecules to become electroluminescent below bandgap voltages, close to their triplet energy, yielding OLEDs operating with a low driving voltage.
The researchers disclosed their results in a Nature Communications paper titled, “Realization of high-efficiency fluorescent organic light-emitting diodes with low driving voltage”, reporting a blue fluorescent OLED more power-efficient than some of the best thermally-activated delayed fluorescent (TADF) and phosphorescent blue OLEDs reported so far, in spite of a lower quantum efficiency.
The deep blue fluorescent OLED tested in the study exhibited a sub-bandgap turn-on voltage of 2.4V, with luminances of 100 cd/m2 and 1000 cd/m2 at 2.9 and 3.4 V, respectively. As a comparison, 3.4V is still less than 50% of the voltage required by other tested blue OLEDs, as the authors highlight – hinting that the novel OLEDs could drastically reduce power consumption for a given brightness.
The research, led by NextGen Nano’s New Fusion division at the NCSU laboratory, means that future OLED display applications could provide superior levels of luminosity while using half the energy, which would also extend the operational life of the device.
North Carolina State University – www.ncsu.edu
NextGen Nano – https://nextgen-nano.co.uk