photoconductive cell

A photoconductive cell is an electronic component that utilizes photoconductivity. This phenomenon occurs when certain materials, typically semiconductors like selenium, experience an increase in electrical conductivity upon exposure to light of sufficient energy.12

Normally, these materials are poor conductors because their electrons are bound. However, when photons with enough energy strike the material, they can excite electrons, allowing them to move freely and conduct electricity. This means that as the illumination increases, the electrical resistance decreases, permitting a greater electrical current to flow. This property makes photoconductive cells useful for detecting light and measuring its intensity, forming the basis for light-controlled switches and other light-sensitive devices.321