The first practical photovoltaic cell was developed in 1954 at Bell Laboratories [5] by Daryl Chapin, Calvin Souther Fuller and Gerald Pearson. They used a diffused silicon p–n junction that reached 6% efficiency, compared to the selenium cells that found it difficult to reach 0.5%.[6] Les Hoffman CEO of Hoffman Electronics Corporation had his Semiconductor Division pioneer the fabrication and mass production of solar cells. From 1954 to 1960 Hoffman improved the efficiency of Solar Cells from 2% to 14%. At first, cells were developed for toys and other minor uses, as the cost of the electricity they produced was very high; in relative terms, a cell that produced 1 watt of electrical power in bright sunlight cost about $250, comparing to $2 to $3 per watt for a coal plant.