Developing blue emission in organic light-emitting diodes (OLEDs) is crucial yet challenging. This paper demonstrates an ultralow voltage turn-on at 1.47 V for blue emission (peak wavelength at 462 nm) in an OLED using a common blue-fluorescent emitter. This is achieved through selective excitation of low-energy triplet states at a low applied voltage, utilizing the charge transfer (CT) state as a precursor and triplet-triplet annihilation (TTA). The OLED reaches 100 cd/m² luminance at 1.97 V.
