@nprofile1q... So, LEDs all of the same color, with phosphors changing the color for them?
I think that was done in the bad old days in order to make a blue LED out of the then-available red and green ones, but brightness was poor because not all of the energy absorbed by the phosphor was re-emitted as light.
That became obsolete when the Nakamura, Amano, and Akasaki developed true blue LEDs. It was quite the adventure, I gather.
https://youtu.be/AF8d72mA41M