1. The impact of temperature on LED chips
Poor heat dissipation will cause the internal temperature of LED Street Light to rise, which will first affect the LED chip. In a high temperature environment, the recombination efficiency of electrons and holes in the LED chip will change. Color rendering depends on the spectral distribution of the light emitted by the chip, and high temperature will change the band structure of the chip, thereby changing the emission spectrum of the light. For example, the energy originally used to excite the phosphor to produce a specific color of light may shift due to the increase in temperature. The emission intensity of some wavelengths of light may be weakened, while other wavelengths of light may be relatively enhanced, which disrupts the spectrum ratio originally designed to achieve good color rendering. Under normal circumstances, high-quality LED chips can accurately emit light of various wavelengths to mix a spectrum close to natural sunlight. When the heat dissipation is poor, this balance is broken, and the color rendering index (CRI) decreases accordingly.
2. Damage to the performance of phosphors
In LED Street Lights, phosphors are the key factors in achieving white light and affecting color rendering. Poor heat dissipation will cause the ambient temperature of the phosphor to be too high. High temperature will accelerate the aging process of the phosphor and reduce its quantum efficiency. Phosphors need to maintain a certain physical and chemical stability in the process of absorbing and converting light. When the temperature is too high, its crystal structure may be damaged, resulting in a decrease in the absorption and conversion ability of light of a specific wavelength. For example, the energy that should have been absorbed and converted into red light may not be effectively converted, resulting in a reduction in the red component in the spectrum of light. The color rendering is reflected by the reasonable proportion of multiple color components. The lack of red components will make the illuminated object look distorted and the color rendering will deteriorate.
3. Destruction of color temperature and color consistency
Poor heat dissipation will also affect the color temperature and color consistency of LED Street Light. As the temperature rises, the color temperature of LED lights will drift. Different color temperatures will give people different visual experiences and also have an important impact on color rendering. For example, LED Street Lights that were originally designed to be warm white temperature (low color temperature) to provide comfortable lighting and good color rendering may become cold white temperature after poor heat dissipation causes the temperature to rise. This change in color temperature will change the effect of light on the color of the object. Moreover, in the same street light or the same batch of street lights, if the heat dissipation is uneven, it will lead to color temperature differences between different areas or different lamps, which will affect the color consistency of the entire lighting area and reduce the overall color rendering effect.
4. Destruction of long-term stability
In the long run, poor heat dissipation performance will cause the color rendering of LED Street Light to continue to deteriorate. Due to the continuous high temperature, key components such as LED chips and phosphors are constantly damaged, and their performance gradually decreases. In the early stage of the use of street lights, the reduction in color rendering may not be obvious, but as time goes by, the color rendering will become worse and worse. This not only affects the quality of lighting, but also may bring safety hazards or affect the business atmosphere for some places that require accurate color recognition (such as commercial pedestrian streets, parking lots, etc.). Therefore, good heat dissipation performance is crucial to maintaining the color rendering of LED Street Light.
