Combinatorial discovery of new thin film photovoltaics

A combinatorial approach to discover new types of thin film photovoltaic devices containing only abundant, inexpensive, and relatively nontoxic elements is described. A large number of compound semiconductors with band-gaps suitable for solar energy conversion (1.0-2.0 eV) are known, including many sulfide compounds, but have not yet been used in efficient devices. Thin films of several sulfide semiconductors will be prepared and their microstructure and optical and electrical properties characterized. Combinatorial methods will be employed to simultaneously prepare many combinations of back contacts, absorber layers, buffer layers, heterojunction window layers, and top contacts. The combinatorial approach is necessary, because existing thin film technologies have largely been selected and improved empirically. The combinatorial approach will enable us to greatly accelerate the rate of empirical discovery.