In recent years, with the rapid development of led technology, the scope of application in the domain of lighting is also expanding. LED landscape lighting, LED indoor lighting, or LED large screens have gradually come to the public’s attention. Plus the improvement of people’s living standards, the improvement of awareness of environmental protection, the pursuit of leisure, and the comfort of the home environment. The lighting of lamps and lanterns has gradually changed from simple lighting function to the coexistence of decoration and lighting. Although incandescent lamps are entering the end of the industry, the alternative products are not only LED lamps. At the same time, compared with energy-saving lamps, LED products do not have a cost advantage, which is the main factor hindering their large-scale development. But from a long-term point of view, LED has its advantages in that other lighting is incomparable.
The obstacles and technologies we need to overcome mainly include the following aspects:
1. luminous efficiency barrier.
The light emitted by LED is monochromatic and does not need extra color film (filter). Moreover, the effective luminous efficiency of the incandescent lamp after adding color film is only 1 / 10 of the original light efficiency of the incandescent lamp. So LED is gradually replacing incandescent lamps with color film because of its high efficiency and energy saving in traffic lights, architectural decoration, automobile warning lights, and other applications. However, most of the lighting sources are white light. At present, people use white LEDs for local lighting, and the energy-saving effect is limited. Only when the luminous efficiency of white LED is much higher than that of fluorescent lamps up to 150-200lm/W will it have an energy-saving effect is the biggest obstacle facing LED light sources to replace traditional light sources is its luminous efficiency.
2. price barriers.
Price is another obstacle that LED light sources to need to overcome to replace traditional light sources. At present, the price of LED light sources is more than $0.10 per lumen, which is more than 100 times the price of an incandescent lamp. Lumilez company of the United States proposed that in the next few years to strive to reduce to $0.01- $0.02 / litre, that is, about 0.1 yuan/litre, equivalent to 60W incandescent LED light source till need to pay 60 yuan, considering the cost performance, will accept special applications. But the cost of getting LEDs into homes as a familiar light source remains a primary obstacle.
3. Fabrication Technology of Power LED.
Power LED is a pivotal device to realize white lighting to replace traditional lighting sources. Its essential technologies include:
To improve the quantum efficiency in epitaxial wafers.
The technicians optimize the epitaxial wafer and improve the process conditions of epitaxial growth. So the internal quantum efficiency of blue, purple, and ultraviolet epitaxial wafers can be close to 95% of the theoretical value.
To improve the external Quantum efficiency of large-size chips.
To obtain large amounts of light energy, large-size power chips are needed. By designing a new chip structure and adopting new processes (such as chip flip structure, ITO electrode, surface coarsening process, surface texture structure, wafer bonding process, etc.), the external quantum efficiency of blue, ultraviolet, and ultraviolet chips is more than 50%.
To improve the light extraction efficiency of the package.
Optimize and improve the packaging optical, thermal, reliability design and process (such as reflecting cup, lens, heat dissipation path, eutectic welding, flexible glueing, etc.).So the light output efficiency of the packaging is close to the external quantum efficiency of the chip.
4. preparation and coating technology of phosphor.
Manufacturing Technology of High-performance Phosphor.
Phosphor is the pivotal material for LED to realize white lighting. It is necessary to develop a phosphor with high efficiency, good color rendering, and stable performance as soon as possible.
Although the yellow phosphor excited by blue light can meet the requirements of white LED products, it still needs to improve its efficiency and reduce the particle size to prepare spherical phosphor. In the structure of blue light + green phosphor + red phosphor, the efficiency of red phosphor needs to be highly improved. Preparation of ultraviolet and ultraviolet LED+ tricolor phosphors, All three phosphors require a high degree of improvement, with red phosphors currently the least efficient. It is necessary to find a material with high efficiency.
Coating technology of phosphor powder.
The coating process of phosphor is usually to mix the glue used for phosphor into fluorescent glue according to a certain proportion and then apply it to the LED chip with a dispensing machine. By optimizing the process parameters such as the ratio of phosphor to glue, the matching of the excitation wavelength of phosphor to the peak wavelength of LED chip, the fluidity and coating thickness of phosphor, the color temperature, and color rendering index, and the lumen efficiency of the white LED is controlled. Make white LED products that meet the application requirements and have a good consistency.
A led light source is a new type of light source with decided directionality, controllability, and color adjustment. Compared with the traditional lighting source, led lighting enters the field of general lighting. The domain of led indoor lighting can not only replace the conventional light source but also develop in a more comfortable and artistic direction. At present, led lights are still rarely seen in the market, the quality is different, and the price is likewise relatively costly. I believe that the popularity of led lighting for ordinary families will become a reality shortly. It may completely replace the traditional lighting source.
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