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Introduction of photoelectric devices

Photoelectric devices refer to devices made according to photoelectric effect, which are called photoelectric devices and also called photosensitive devices. There are many kinds of photoelectric devices, but their working principles are all based on the physical basis of photoelectric effect. The types of photoelectric devices mainly include photovoltaic cells, photomultiplier tubes, photoresistors, photodiodes, phototransistors, photovoltaic cells and photoelectric coupling devices.

The structure, working principle, parameters and basic characteristics of these photoelectric devices are introduced below. The conductivity of semiconductor materials is determined by the carrier concentration. Carriers in semiconductor materials include free electrons in the material and vacancies left by them.

Under normal circumstances, the formation and recombination of free electrons and holes are in dynamic equilibrium. If an electron wants to overcome the atom's bondage and become a free electron, it must absorb energy, and illumination can provide energy for the electron and enhance its ability to get rid of the atom's bondage.

The original dynamic equilibrium is broken, and the formation rate of free electrons and holes is greater than the recombination rate, thus forming free electron-hole pairs in semiconductors. Therefore, illumination can change the concentration of carriers, thus changing the conductivity of semiconductors.