Since the energy of the generated photons varies with the manufacturing materials of LEDs, the industry controls the wavelength of LED light emission through manufacturing materials, thereby producing various LEDs with different spectrums and colors.
The material used in the world’s first LED is arsenic (As) gallium (Ga), the operating voltage is 1.424V, and the light it emits is infrared spectrum. After that, the industry developed phosphor (P) gallium (Ga) as the LED material, the working voltage is 2.261V, and the emitted light is green light. In the early stage of the industry, through the materials required for these two types of LEDs, LED products with all wavelengths ranging from infrared to green light were prepared, and common red LEDs, yellow LEDs, orange LEDs, etc. were developed. Large LEDs are called 3-element LEDs because they use three elements, gallium, arsenic, and phosphorous, while blue LEDs, green LEDs, and infrared LEDs are called 2-element LEDs. The industry later developed a 4-element LED that uses a mixture of four elements, aluminum (Al), calcium (Ca), indium (In), and nitrogen (N), which can emit light in all visible light ranges and part of the ultraviolet spectrum.