If solar cells could be printed onto window shades and sold inexpensively, they might open up new markets to average-income homeowners as well.
What if you could print a solar cell using a printing process that uses vapors, not liquids, and temperatures lower than 120°C? This would make it possible to use ordinary paper, plastic sheets, or textiles as the substrate for the solar cell. To do the printing of this PV, five layers of materials must be deposited using vapor deposition on the same sheet of paper in separate passes and using a mask made of paper to form the patterns or arrays of cells on the surface. The whole process has to take place in a dedicated vacuum chamber.
Researchers at MIT, led by Vladimir Bulovic, director of the Eni-MIT Solar Frontiers Research Center in Cambridge, MA, have printed solar cells on PET substrates using this method. They can fold and unfold the printed results repeatedly 1000 times as a method of stress testing. Result: no significant loss of performance. Researchers plan to fabricate scalable solar cells that can reach high watts-per-kilogram performance.
There are, however, some problems with PV cells printed on ordinary paper. The cells have an efficiency of approximately 1%, and that’s enough to power a small electric gizmo, Bulovic says. With fine tuning, the conversion factors will improve, researchers say. As a low-cost alternative to the glass-substrate-printed conventional solar cells produced today, conductive inks printed on flexible substrates could be affordable, even in remote, rural areas. If solar cells could be printed onto window shades and sold inexpensively, they might open up new markets to average-income homeowners as well.
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