How did blue LEDs make white LED household bulbs possible?

Before the invention of the blue LED, it was impossible to create white light using light-emitting diodes because white light requires a combination of red, green, and blue light. While red and green LEDs had long existed, the development of a blue LED remained a significant challenge until researchers successfully utilized gallium nitride (GaN) to create high-quality crystals and p-type semiconductors.1

Once efficient blue LEDs were developed, they became the essential component for producing white light. By combining the blue light emitted by these LEDs with phosphors—materials that emit light when exposed to radiation—manufacturers could convert the blue light into a broader spectrum that appears white to the human eye. This breakthrough paved the way for the energy-efficient LED household bulbs used for general illumination today.12