Answer:
The predominant way people make solar cells is through two layers of silicone that are separated by a permeable film. There are other ways to make solar cells. There is a design on the net to make a cell out of Titanium Dioxide (TiO2) and raspberry juice.
Whoever had enough time... and was bored enough to figure this out, well, my hat's off to you. Wish I had your time :)