Peak wavelength: No matter what material is made of LED, there is a place where the relative light intensity is the strongest (the light output is maximum), and there is a wavelength corresponding to it. This wavelength is called the peak wavelength and is represented by λp. Only monochromatic light has a wavelength of λp.
Dominant wavelength: Some LEDs emit more than a single color, that is, not only have one peak wavelength; they even have multiple peaks, which are not monochromatic light. To describe the chromaticity characteristics of LEDs, the dominant wavelength is introduced. The dominant wavelength is the wavelength of the dominant monochromatic light emitted by the LED that can be observed by the human eye. The better the monochromaticity, the λp is the dominant wavelength.
