WikiHow has a piece on how to make a photovoltaic solar cell from some common household ingredients and a piece of conductive glass (which you can buy online). The main ingredient in the cell is a titanium dioxide (TiO2) solution. You make this from the powdered sugar found in white powdered donuts.
The process of making the cells is only ten steps and basically involves filtering out the titanium dioxide from the donut powder and preparing a solution from it, coating the conductive glass with the TiO2, heating it to fix it to the glass, and soaking the cell in hibiscus herb tea (teas contain organic compounds known as anthocyanins which are good at capturing light in the visible spectrum). With that part of the cell done, you then create a second layer of conductive glass, covering it in graphite (pencil) lines to create a counter-electrode.
Now all you have to do is combine the two glass pieces (separating them with spacers or strips of tape) and introduce an electrolyte between them. You make this electrolyte solution by combining 3 parts iodine and one part alcohol. Before using the cell, you squirt some of this electrolyte between the two glass plates with an eyedropper and then you clamp the two plates together using binder clips. Your cell is now ready to be placed in the sunlight and hooked up to a multimeter to test for how much current it is generating.
That’s it! You have just made your own PV solar cell at home and now have a bag of powered donuts waiting for you to munch on while you experiment with what kind of electrical current you can produce when exposing the cell to a light source.
The full details of the project steps can be found on this WikiHow page. This project would make a really fun home science experiment for the kids.
Note: You can actually buy titanium dioxide online for under $7 for a half pound. But then, where would your excuse for eating all those donuts come from? Forget I told you this. Donuts it is!