Alta Devices has been in the thin-film GaAs space for years. They've attracted nine-figure investments and posted really spectacular efficiency of ~28% in GaAs thin films. It's all very exciting, but these discoveries are not untrodden ground.

http://en.m.wikipedia.org/wiki/File:PVeff(rev131204)a.jpg

http://www.greentechmedia.com/articles/read/Sources-Alta-Dev...