OLED is a thin-film device in which an organic light-emitting unit is sandwiched between positive and negative electrodes.
Organic light-emitting unit typically consists of three layers, i.e., a hole-transporting layer, emission layer, and electron-transport layer.
OLED exhibits superior characteristics such as ultrathin thickness, no short-wavelength blue light, and low power consumption. Now, OLED displays are already being used in smartphones, smart watches,and the large-size televisions in our daily life. Further, eye-friendly OLED lighting will become spread within the coming years.