Phosphorescent organic light-emitting diode
Phosphorescent organic light-emitting diodes (PHOLED) are a type of organic light-emitting diode (OLED) that use the principle of phosphorescence to obtain higher internal efficiencies than fluorescent OLEDs. This technology is currently under development by many industrial and academic research groups.
https://en.wikipedia.org/wiki/Phosphorescent_organic_light-emitting_diode