Silicon might not be the best material to begin with. It is the most popular because  they have spent more time tweeking that one material. It being the most difficult to grow as a single crystal wafer to obtain a higher level of purity has been the solar industries focus.
  The properties of silicone which lead to a reaction favorable to convert light are more important then the silicone itself. High output cells verses low output cells and why.
   I picture there being a 1-2-3 process. High wide dirty light vibration in ,then means to filter vibration to enable to separate layers one diamagnetic one magnetic both translucent and thin and able to become polarized with the electrodes stuck on the outsides. One has to allow some light to pass through the top all the way to back side electrode. Some classes of material dissolve in an alkali some in acids the dye is the filter that knocks the vibration back to a cleaner rate of vibration on the back side compared to the chaotic rate on the front side thereby creating a potential difference front to back. If you cant make a pure crystal and cut into a wafer maybe there is a way to bias a bunch of tiny particles by introducing a range of vibrations to a thin layer of random crystal layer to cancel out part of the light spectrum as it passes to the back electrode. A choke of sorts, but more in line with the way sound canceling works. Does a typical solar cell show that proximity to high frequency disturbances effects the output? I dont have a signal generator maybe just a speaker and win amp will suffice and a cheap solar powered calculator.
  If so then you can use any opposite materials that will satisfy the other requirements of being translucent conductive and either more P or N in nature. If an outside range of frequency will F up a cell maybe the right one will improve it or open up the door to a number of better easier materials that are free.
  As far as giving power back to the grid they can kiss my butt.I would rather send the extra to ground and fry worms or power a foam finger with the extended finger moved to the position of the middle finger tied to a motor to wave at the utility company trucks when they drive by.
   Im thinking zirconium