Homemade Copper Solar Cells

Selenium was extensively used in the production of commercial
solar cells before silicon. Although it can be a somewhat
difficult to find a supplier and it is a toxic heavy metal, it is
relatively inexpensive and can often be found in old model radio
sets, where it was used in the rectifier of the power supply.
A selenium photocell is made from a metal plate (usually iron)
with one side being covered with a layer of selenium. A very thin
layer of silver or gold is spattered over the selenium layer forming
a layer of current-carrying material that allows light to pass through
it. This layer is called a transparent electrode. A metal electrode
called a collector, rests on the gold or silver near the edge of it.
Wires are attached to the collector and the iron plate to deliver
the electric current to the load. Although not as great an output
as more modern cells, a selenium photocell can produce as much
as eight milliamperes for each square inch of surface area exposed
to bright sunlight.
Cadmium sulfide is probably the most promising low-cost
solar cell second only to silicon.
If you have an interest in electronics, you will undoubtedly
recognize cadmium sulfide (the common "CDS" cell) as the
material used in light detecting circuits. Although inventors
have realized for some time that a number of materials such as
cadmium sulfide change their electrical resistance in the presence
of light, it has only been in fairly recent times that it was
realized they could also be used to generate power also.
The most important attribute of cadmium sulfide is that it
could be mass-produced efficiently using a thin-film procedure
wherein very thin layers of its photosensitive components are
evaporated onto a base metal or screen printed.
Cadmium cells are fairly efficient (3-5 typical) making
them a good rival for amorphous silicon cells.
An Experimental Cell With Cuprous Oxide
The best cell by far for the you to start with, is a cell made
with cuprous oxide (Cu^O). Copper actually has two oxides, a red oxide called cuprous oxide, and a black oxide called cupric oxide
(CuO).
The dark red cuprous oxide has photoelectric properties but
black cupric oxide does not. The black oxide that forms on the
outside of your cell must be removed because it is opaque and
will not allow light to reach the cell's active surface.