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Credit: Jameson Simpson

Start the Circuit
To generate and transmit electricity, solar cells need to have a circuit. First, an anode—typically indium tin oxide (ITO)—for this circuit needs to be formed onto a plastic, quartz, silicon, or glass substrate. Two common application methods to accomplish this are sputtering (shown) and chemical vapor deposition. Both deposit a 50- to 300-nanometer-thick ITO layer onto the substrate at temperatures around 550 C to 605 C (1,022 F to 1,121 F).


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Credit: Jameson Simpson

Deposit the Window Layer
The interfacial, or window, layer goes on top of the anode and will keep electrons flowing through the solar cell, allowing each electron to be harnessed and turned into energy. The 1- to 2-micrometer-thick layer comprises a mixture of polymers and materials, which are deposited by evaporating the molecules at high temperatures, similar to the ITO’s application. The specific makeup of the window layer will depend on the type of active layer—the next component—used in the photovoltaic (PV) cell.


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Credit: Jameson Simpson

Apply an Active Layer
The most important part of the solar cell is the active layer, which will capture and collect the photons of light. The four main types of solar cells are amorphous silicon, cadmium telluride, copper indium gallium selenide (CIGS), and organic. Amorphous silicon PV cells are the easiest to manufacture because the technology is mature, but their conversion efficiency is comparatively low at 12.2 percent. CIGS have an efficiency of 19.9 percent, but their production process still requires optimizing. Regardless of type, the active layer will run about 1 to 4 micrometers thick and be deposited through evaporation methods.


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Credit: Jameson Simpson

Assemble the Film
The active layer is topped by a second window layer and then a cathode layer, which is typically aluminum and just a few nanometers thick. The cells can now be printed on films either in large rolls or on individual flat sheets, which will then be cut to size. The thin-film photovoltaic is now ready for installation. When sun hits the solar cell, the light photons are trapped by the active layer, funneled along the cell by the sandwiching window layers, and then converted into electricity at the anode and cathode.