Couldn’t we have a lead box lined with these radiation to electricity converters with a small amount of radioactive material in the center, and have an energy generating device that would last for thousands or even millions of years? Imagine putting the sun in a box lined with solar cells, but on a much smaller scale.
Is there a reason this wouldn’t work?
Scintillaton is another option. Use alpha and beta decay to push electrons up in their orbits, to decay and release a photon. Then capture and convert that photon to electricity with photovoltaics.