Researchers at Binghamton’s Center for Autonomous Solar Power create solar cells using materials that are abundant on earth. A typical cell is 1 centimeter long and half a centimeter wide, with several layers about a hundred times thinner than a single human hair.
The scientists begin with glass slide coated with molybdenum, a metal with an extremely high melting point.
The four component materials (copper, zinc, tin and sulfur) are deposited onto the glass in layers in a sputtering chamber.
The cell is annealed, in a heating process akin to baking. At this point, the positive side of the diode is ready.
Now it’s time to prepare the negative part of the diode, which is almost 10 times thinner than the positive (CZTS) layer. Using chemical-bath deposition, a layer of cadmium sulfide is applied to the cell. (If you think of the positive side of the solar cell as a layer cake, this is the yellow frosting.)
Next, transparent conducting oxide is applied, using a sputtering system or atomic layer deposition.
At this point, scientists create a grid that they call “fingers,” providing a wire so the cell can be attached to a device.
Now the cell is ready for testing. Solar cells are evaluated based on the percentage of available solar energy that they convert to electricity. The materials CASP is using have the potential to reach 30 percent efficiency. A breakthrough like that would make solar energy a better option than coal or nuclear power.