All the power currently used by humans could be provided sustainably by solar cells deployed over just 0.3% of the land area of the Earth. Three technological barriers prevent our civilization from being sustained entirely by solar energy, a feat accomplished by almost all other species on Earth: 1) Current PV technologies use elements (silver, tellurium, gallium and indium) that are too rare to cover the required area. 2) PV modules are too complicated, with too many separate pieces and wires connecting them. 3)  Their production rate is too slow. We review our research toward replacing the rare elements with common, abundant elements (such as copper, zinc, tin, sulfur and oxygen). Promising Earth-abundant absorber layers include Cu2O, SnS, Cu2ZnSn(S,Se)4 and (CH3NH3)Pb(I,Cl)3. Current complicated structures with wires connecting individual silicon cells must be replaced by integrated interconnections, just as computers have advanced from discrete wiring to integrated circuits. Faster production requires speeding up the kinetics of depositing the layers during an integrated, continuous process. A good model for such an inexpensive continuous process is the chemical vapor deposition of fluorine-doped tin oxide on flat glass during its production by the �float� process. This process produces large amounts of inexpensive low-E glass for energy-conserving windows in buildings. This same SnO2(F) coating is the transparent conductor that is then cut into pieces onto which semiconductor CdTe and then a back metal contact are deposited to make the least expensive solar cells. What is needed is to deposit continuously an Earth-abundant semiconductor and a back metal contact on top of the SnO2(F) just formed on the glass production line. When all these improvements are achieved, PV can become the sustainable basis for powering our civilization.

Why don't we have inexpensive PV systems made from Earth-abundant elements?

248th National Meeting (2014)

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