LED and OLED: a lamp and a dress

LED life can reach more than 100 thousand hours, a person can use a lamp. OLED has a special flexibility, the future of the clothes is the screen, what kind of color to show what kind of color, a person can wear a dress. -- Wen Shangsheng

The screen can be bent, the mobile phone can be folded, as thin as paper TV screen; daytime transparent windows let in the light, the night becomes a source of light; navigation information can be through the windshield of the car to play. The beauty of these future electronics, thanks to the OLED technology. So OLED will eventually dominate display and lighting in the future.

OLED working principle

OLED refers to the phenomenon that the organic semiconductor materials and luminescent materials are driven by electric field. The principle of using ITO transparent electrode and a metal electrode as anode and cathode devices, driven in a certain voltage, the electrons and holes are through electron and hole transport layer migration to the light emitting layer, and meet in the light emitting layer, and the exciton luminescence molecules excited by luminescent molecules emit visible light radiation. The radiation can be observed from the side of the ITO, and the metal electrode film also acts as a reflector. From the point of view of the current status of the development of organic light emitting devices, green light, blue light, red light are related to the development of materials, in which the most mature green technology.

White light OLED

For the realization of the white light OLED lighting, there are two main methods: first, the wavelength conversion method is to use the blue light emitting OLEDs yellow, orange, red phosphor or phosphor to achieve white light. Two, the color mixing method, is the use of blue and orange light two kinds of compensation light or red, green, blue three kinds of primary colors of light doping or multi-layer way to achieve white light method.

The theory of the optical efficiency of OLED can reach 200lm/w; OLED in lighting applications on industrial targets in 1.000cd/ square meters, up to 50~80lm/w efficiency; at present, for the optical efficiency of up to 60lm/w white OLED lighting products more than 80 color index.

OLED lighting applications

The use of large area advantages of OLED lighting, OLED light source can be installed in a large area on the ceiling and walls, ceiling and wall surface so that the whole issue is the entire surface of the soft light, not like a light bulb, fluorescent lamp is local lighting, light source makes people feel more comfortable and gentle.

The utility model can also be matched with the design of the lighting mechanism, and the utility model can be used to produce a vertical hanging type lighting lamp, which can be provided with an adjustable lighting device. Can also be used with OLED lighting light, thin features, in addition to the design of sheet lighting, so that the light can be light swaying in the wind, so that the general lighting can show a different situation of lighting. OLED lighting can make the lighting design more freedom, so that lighting can show more application scenarios.

Comparison of OLED and LED lighting

From the point of view of lighting demand, LED is a point of light, lighting light concentration, applied to the outdoor environment is more eye-catching, suitable for local area lighting, advertising signs, traffic warning signs and other applications. OLED belongs to the surface of the light, the light is more soft and uniform, better indoor effect. Two each one has his good points.

From the lamp design, LED heating, external lampshade, cooling device, light scattering device, lighting design is more complicated: the plane light source characteristics of OLED, except for the various types of lighting design, thermal performance also and does not need additional cooling pad high cost element lamp. The future realization of flexible substrate OLED lighting, lighting designers to create an unlimited imagination. From this point of view, OLED better.

From the optical efficiency of LED chip, the luminous efficiency can reach more than 120lm/W, when additional lamps, due to the effect of shade, light scattering device, the actual efficiency may be reduced to around 60~70lm/W; OLED lighting currently can only 30~50lm/W, there is still a large gap between different materials, the performance differences, the need for further efforts in materials research and design of device structure.

To create cost, LED with the expansion of production capacity and technological progress, the price gradually lower, has gradually narrowed the gap between traditional lighting. OLED lighting prices are still too high, mainly because of high cost of OLED lighting materials, coupled with the mainstream of the evaporation process to enhance the efficiency, so the material utilization rate is not high, and high production cost of OLED lighting pad.

The service life of the product, LED lighting can theoretically reach 100 thousand hours, of course, there is a heating effect life, depreciation and other problems in the process of using OLED devices; life is seriously insufficient, generally only 5000-8000 hours, which is also restricting the market application of the most serious obstacles, OLED lighting applications to gain popularity. Also, we must further improve its service life, the initial goal is to reach the level of fluorescent lamp, which is 20000 hours, and the next goal is to reach 50000 hours, to achieve this goal, the materials have a big breakthrough and a high into the device structure and process.

On the whole, OLED and LED belong to solid-state lighting, has low heat, low power consumption, fast response, small volume, high impact loading and seismic characteristics easy to develop into a short thin products and other advantages, but in terms of technology maturity and commercialization of LED, and there is still a certain gap.