As a new type of semiconductor lighting technology, LED and OLED are called the fourth generation lighting source or green light source. Compared with traditional lighting products, LED has the features of energy saving, environmental protection, long life and small size, and can be widely used in various fields such as indication, display, decoration, backlight, general lighting and urban night scene.
Therefore, in recent years, some economically developed countries in the world are actively developing LED and OLED semiconductor lighting.
However, LED and OLED have their own characteristics due to their different working principles and production processes.
The full name of LED is light-emitting diode, which is generally manufactured by iii-iv inorganic semiconductor materials and chemical vapor deposition (CVD) process.
As in the traditional semiconductor industry, the manufacturing process is expensive and difficult to achieve large size.
Therefore, leds can only be used in the form of point light.
In the field of indoor general lighting, in order to achieve the illumination brightness of a certain space, LED needs high luminous brightness. Therefore, in order to avoid dazzling and produce soft light, LED often must be equipped with a lampshade for use.
As a result, LED lighting efficiency will be reduced.
If you want to use LED to make face light source, for example, as the backlight of LCD, you need to combine multiple LED and match with complex optical system such as the light guide plate.
In addition, the LED's luminous efficiency drops sharply as the temperature rises.
As the size of LED is very small, it is difficult for the heat generated during operation to be distributed in time. Therefore, it is necessary to equip LED lamps with radiators.
Based on the above reasons, the advantages of LED light source technology, such as luminous efficiency, lightness and cost advantages, will be greatly discounted after the lamp is made.
At present, white LED is generally realized by covering phosphor on blue LED (as shown in the figure).
The phosphor is excited by the blue light emitted by the LED, which produces yellow light, and then mixes with the blue light of the LED itself to produce white light.
This approach, though low in cost, has many drawbacks.
On the one hand, the color index of the white light produced in this way is not ideal, that is, the color of the object under the exposure of this white light will appear deviation, making it unsuitable for the application of high color quality;
Phosphor, on the other hand, ages much faster than blue leds, causing the white light to drift towards blue, shortening its life.
OLED is an organic light-emitting device, as the name implies, OLED is based on organic semiconductor materials.
OLED materials are divided into small molecules and high polymers. At present, the main industrialized materials are small molecules and organic materials.
OLED is a primordial face light source technology because it USES low-cost glass as the substrate and is manufactured using a large area vacuum thermal evaporation film forming process.
OLED process technology without LED process of ultra-high vacuum and high temperature environment, cost competitiveness is much higher.
In theory, organic materials are much lower than inorganic semiconductor materials, but the cost of organic materials is still very high due to the limited industrial scale and the utilization rate of materials in production.
But the cost of organic materials will fall sharply as the industry expands.
OLED usually glows evenly and softly and is close to lambert radiation distribution. Therefore, OLED itself is almost a lamp without matching lamp cover.
Currently, white light OLED mainly consists of three basic colors: red, green (yellow) and blue.
In addition, the luminescence spectrum of organic materials is characterized by its wide half-wave crest, so there is no large gap in the spectrum of white light OLED, which makes the color index of OLED light source excellent, especially suitable for indoor general lighting and even professional photography applications.
Moreover, by adjusting the luminescence ratio of each color material, the light of any color can be produced to adapt to different applications.
Because OLED has a very large luminous area, the heat generated while working can be distributed in a timely manner, without the need for cooling devices.
So OLED can be very thin and space-saving.
In addition, OLED can be designed into a variety of shapes, greatly expanding the application space of OLED lamps in the field of art decoration.
OLED killer transparencies can even be used in ways that are completely unimaginable with traditional lighting, such as making OLED on window glass, letting natural light in during the day and using it as lighting at night.