Blue organic light-emitting diode with a turn-on voltage of 1.47 V

, which is equivalent to the luminance of a typical commercial display, at 1.97 V. Blue emission from the OLED is achieved by the selective excitation of the low-energy triplet states at a low applied voltage by using the charge transfer (CT) state as a precursor and triplet-triplet annihilation, which forms one emissive singlet from two triplet excitons.