I think your concerns are addressed a bit toward the end of the article > Other approaches to improving the efficiency of solar cells tend to involve adding an

I think your concerns are addressed a bit toward the end of the article > Other approaches to improving the efficiency of solar cells tend to involve adding another kind of cell, such as a perovskite layer, over the silicon. Baldo says “they’re building one cell on top of another. Fundamentally, we’re making one cell — we’re kind of turbocharging the silicon cell. We’re adding more current into the silicon, as opposed to making two cells.” The opening sentence is accurate -- "conventional" silicon solar cells are exactly what this work is improving.