The joule thief is excellent for letting you run a bright white led from a single 1.5V cell. I had a flashlight like that although I didn't see what circuitry was inside, to boost the voltage.
The joule thief is simple and easy for us to make from a ferrite bead. However to fabricate it on a chip, then there is the question how to fabricate the inductor...
Whether it has to be an external component, or whether there is some arrangement of tiny traces that can fit on the chip. Also what frequency of operation is compatible.