Introduction to 0LED:
OLED (Organic Light-Emitting Diode) is also called OEL (Organic Electro Luminescence), which means that organic semiconductor materials and organic luminescent materials are driven by electric fields and are injected and recombined by carriers. Luminous technology. The principle is to use ITO glass transparent electrode and metal electrode as the anode and cathode of the device respectively. Under a certain voltage, electrons and holes are injected from the cathode and the anode to the electron transport layer and the hole transport layer, respectively, and then migrate to the light. The layers form excitons to cause the luminescent molecules to excite, and the latter emits visible light after being irradiated. Radiation light can be observed from the ITO side, and the metal electrode film also functions as a reflective layer.
The origin of OLED:
The history of OLEDs is later than inorganic materials such as electroluminescence (LED). In 1936, Destriau dispersed the organic fluorescent compound into a polymer to form a thin film, and obtained the earliest electroluminescent device. In the 1950s, people began to explore electroluminescent devices with organic materials. A. Bernanose et al. observed the luminescence phenomenon by adding a DC voltage of 400V on both sides of a single chip. Since the single crystal is 10 mm to 20 mm thick, The drive voltage is higher. In 1963, M. Pope et al. also obtained electroluminescence from a single crystal. In 1987, Deng Qingyun of Kodak Company first developed a practical low-drive voltage (<10V, >1000cd/m2) OLED device (Alq3 as a light-emitting layer). In 1990, Burroughes and his collaborators at the University of Cambridge in the UK successfully researched the first polymer organic electroluminescent device (PLED) (PPV as a light-emitting layer), and further laid the foundation for the practical application of organic electroluminescent display devices. In the Forrest group, the electrophosphorescence was obtained by doping heavy metal compounds, and the triplet excitons in the excited state were used to greatly improve the internal quantum efficiency of electroluminescence.
At present, more than 100 research units and enterprises in the world have invested in the research and development and production of OLEDs, including display giants on the market, such as Samsung, LG, Philips, Sony and other companies. On the whole, the industrialization of OLED has begun. Among them, monochromatic, multi-color and color devices have reached the level of mass production, and mass production of large-size full-color devices still has difficulties.