22.1 The Photoelectric Effect

The evolution of both photoelectric technology and quantum theory occurred simultaneously.  The first crude solar cells were developed at the turn of the 19th century after the interaction between radiation and metal surfaces was observed by Heinrich Hertz in his classic experiment to produce and detect EMR.  In 1905 Einstein explained this effect using quantum theory and was awarded the Nobel Prize for it in 1921.  By that time, quantum theory had become mainstream in scientific circles.  In 1954 Bell Laboratories accidentally discovered that silicon, when mixed with certain metal impurities, was very sensitive to light.  Four years later, in 1958, both Russian and American satellites deployed solar cell technology to power their satellites.  Today, thanks to applications in space exploration and research and an understanding of quantum theory, photoelectric technology is deployed in countless applications, from automatic door openers, to remote pumping stations in northern Alberta, and even to the battery chargers that power the Spirit and Opportunity rovers on Mars.