oled
OLED stands for organic light-emitting diode. The device produces light through electrically driven excitation and recombination in organic semiconductor layers. Its optical function differs from a liquid-crystal element that modulates an external light source. In a display, the OLED emitter is one part of a larger pixel, drive-circuit, and encapsulation system.
Tang and VanSlyke’s 1987 paper is a landmark in practical organic electroluminescence. The Applied Physics Letters work described a thin-film organic device with a double-layer structure. Its significance lies in the coordinated transport and emission structure. The research milestone should be distinguished from later display commercialization, manufacturing scale-up, and subsequent emitter technologies.
Charge transport and light generation require coordinated materials. Electrodes inject carriers, transport layers guide them, and the emissive region converts part of the electrical input into light. Energy-level alignment and exciton behavior influence efficiency. Optical extraction also matters because generated photons do not all leave the device in useful directions.
An active-matrix display uses transistors to control the emitters. The backplane stores and regulates pixel drive conditions, while the organic diode supplies light. Semiconductor technologies such as low-temperature polysilicon or oxide TFTs address backplane requirements. Calling a display OLED identifies the emitting principle rather than uniquely specifying its transistor material.
Lifetime and uniformity are system-engineering constraints. Moisture protection, material stability, current distribution, and differential aging influence long-term image quality. Color and brightness performance depend on the complete stack and driving conditions. A useful OLED comparison therefore combines emitter physics, backplane behavior, optical design, and measured operating life.
Sources and further reading. [Tang and VanSlyke, Organic electroluminescent diodes, 1987](https://doi.org/10.1063/1.98799); [Society for Information Display OLED milestone chart](https://www.sid.org/Portals/sid/Files/pdf/20121024%202.a.1.c%20EL-OLED%20DTMC%20%20%28Display%20Technology%20Milestone%20Chart%29%20.pdf).
Read OLED as an organic electroluminescent device whose display performance depends on materials, drive circuitry, optics, and protection.