As far back as the 1800s scientists realized that, through certain chemical reactions, sunlight could be converted into electricity. The first experimenter to successfully accomplish this feat was A. E. Becquerel (1820-1891), who built a device that could measure the intensity of light by observing the strength of an electric current produced between two metal plates. Later scientists discovered that the metal selenium was particularly sensitive to sunlight, and during the 1880s Charles Fritts constructed the first selenium solar cell. Fritts's device was woefully inefficient, however, converting less than one percent of the received light into usable electricity.

The Fritts selenium solar cell was mostly forgotten until the 1960s when the drive to produce an efficient solar cell was renewed. It was known that the key to the photovoltaic cell was in creating a semiconductor that would release electrons when exposed to radiation within the visible...