It is in this context that the hyperfluorescence (HF) emitters are emerging. Indeed, they have been referred to as the fourth generation on OLED active layers. HF is defined as the emission mechanism that combines two different emitters, such as TADF and fluorescence emitters (Fig. ). As stated, TADF molecules have a small energy gap (EST) between the singlet and the accepting triplet energy states. This permits the upconversion of excited energy from accepting triplet to singlet states, which provides efficient emission from the singlet state. However, if the excited energy produced by the TADF emitter is harvested by a fluorescent molecule following the Förster resonance energy transfer (FRET) process, this will emit four times more photons than conventional fluorescence at the same excitation conditions. In addition, HF emitters display a strong and narrow-band emission, contrary to the broad emission of TADF emitters. Therefore, HF has been established as a promising approach to designing OLEDs with high color purity and enhanced stability. The study of HF emitters and their optoelectronic applications is progressing with momentum. In this mini-review, we systematically documented the molecular design principles of HF emitters, their fundamental photophysical requirements, and the advances in HF-OLED.