Page 28 - ISES SWC50

4. PRE 1950

4.1 PV Pre 1950
1839
• French scientist Edmond Becquerel discovered the photovoltaic effect while experimenting with an
electrolytic cell made up of two metal electrodes placed in an electrically conductive solution where the
electricity generated increased when exposed to light.

1873:
• Willoughby Smith discovered the photoconductivity of selenium.

1876:
• William Grylls Adams and Richard Evans Day (UK) discovered that selenium produces electricity
(photovoltaic effect) when exposed to light. Although selenium solar cells failed to convert enough sunlight
to power electrical equipment, they proved that a solid material could change light into electricity without
heat or moving parts.
1883
• Charles Fritts (USA) created the first working selenium cell. He coated selenium with a thin layer of gold
and the first functional solar cell had a conversion of 1%

1887
• Heinrich Hertz (Germany) observed the photoelectric effect. The Photoelectric effect is the phenomenon in
which electrically charged particles are released from or within a material when it absorbs electromagnetic
radiation. The effect is often defined as the ejection of electrons from a metal plate when light falls on it.

1904
• Albert Einstein (Germany) described in theoretical detail the photoelectric effect.

1916
• Robert Milliken (USA) proved the photoelectric effect theory in experiments.

1914
• Goldman and Brodsky (USA) correlate the photoelectric effect with the existence of a barrier to current
flow at a semiconductor metal which helps to provide insight into building practical photovoltaic devices.

1918:
• Jan Czochralski (Poland) discovered a method, known as the Czochralski process, for monocrystalline
silicon production.

1921
• The Nobel Prize in Physics 1921 was awarded to Albert Einstein «for his services to Theoretical Physics,
and especially for his discovery of the law of the photoelectric effect.»

1932
• Audobert and Stora discovered the photovoltaic effect in Cadmium Selenide (CdSe).

1940/41
• In 1940 Russel Ohlworking at Bell Laboratories discovered the P-N junction. In 1941 henoticed the effect
on light on the junction basicallycreating a solar cell.
4.2 Solar Thermal Pre 1950

1767
• Horace-Bénédict de Saussure built his “hot box” plate collector.

10 | ISES SWC50 - The Century of Solar-Stories and Visions