Can one use infrared to generate the energy, as it is easy to make IR emitters. Perhaps carbon nanotubes which would absorb broad spectrum light, and re-emit IR, although it may not be in a single wavelength.
One problem is that I assume emissions are omnidirectional. So, if one thinks like a cube, then at least 1/6 of the light would be re-emitted back towards the source, and thus would be lost. On a plane, the loss could be much higher.
Adding more places for loss of energy also seems dangerous, so while the absorption of red might be twice as efficient for energy input as violet, that added efficiency could be quickly lost. Nonetheless, it is worth trying.
As far as the triple junction cells, they are most efficient on Earth with concentrated light which means that they must have a solar tracking system. It is likely that one of the differences between terrestrial solar panels and space solar panels is the broad frequencies of light that is absorbed by our atmosphere.
It is quite possible that the Per-Anders Hansen system would also benefit from concentrated light.