Russell Ohl

Russell Ohl was an American engineer at Bell Telephone Laboratories who in 1940 discovered the p-n junction in silicon and observed that a piece of silicon with such a junction generated a substantial electric current when exposed to light, the effect that underlies every modern silicon solar cell. Ohls discovery, made while he was investigating silicons usefulness for radio detectors rather than searching for a way to convert light to electricity, was recognized as far more efficient than the earlier selenium photovoltaic effect that Charles Fritts had used in the 1880s. His 1941 patent on the silicon photovoltaic device is considered the direct technical ancestor of the silicon solar cell that Bell Labs researchers Chapin, Fuller and Pearson would build into the first practical solar battery in 1954. Ohls discovery of the silicon p-n junction also underlies the semiconductor diode and transistor technology that transformed electronics generally.