Right, you don't get all the way there with one layer. But perovskite layers can usefully be thin enough that light of too long wavelength for one layer goes ri

Right, you don't get all the way there with one layer. But perovskite layers can usefully be thin enough that light of too long wavelength for one layer goes right through to the next. Three layers is wholly practical, because perovskite layers are cheap. So, top layer converts UV and blue photons. Next catches maybe green to orange. Bottom catches red and IR. Multi-layer silicon would be expensive.