Why phosphorous used in CRT?

CRT televisions consist of a controlled flow of electrons hitting precisely at phosphor dots of colours red, green and blue, arranged behind the glass screen of the television set.

When an electron hits one of these phosphor dots, the respective colour of the phosphor dot shines for a very short duration. This is the basic principle of the working of the CRT.

Thus, phosphor plays a very important role in the generation of colour pictures in the CRT