Yes, I noticed that as well Metabill and wondered what, exactly, the TJ solar cell is.
Found this today..someone is making headway, but it mentions only a single junction. Was Dr.T's TJ 3x better?
http://www.compoundsemiconductor.net/article/95449-us-sunshot-initiative-supports-gaas-film-on-low-cost-substrates-project.html