read a blurb about a year ago. most of the solar cells are made from leftovers from the chip industry (selenium,gallium, etc.). There was also a blurb on a magnetic crystal one way glass that uses the same (similar) technology. Also a blurb on the flexible cells which appear to be almost an aluminum fabric type (thin wire mesh).
Don't have a link to any of it though. seems the efficiency being low on most of the solar cells has to do with them only converting certain wavelengths- the infrared spectrum is a little larger (longer wavelength?).