1. Working principle: The working principle of the photoresistor is based on the internal photoelectric effect. Install electrode leads on both ends of the semiconductor photosensitive material, and package them in a tube shell with a transparent window to form a photosensitive resistance. In order to increase sensitivity, the two electrodes are often made into a comb. The materials used to make photoresists are mainly metal sulfides, selenides, tellurides and other semiconductors. Usually, coating, spraying, sintering and other methods are used to make very thin photoresistors and comb shaped ohmic electrodes on the insulating substrate, connect the leads, and package them in a sealed housing with a light transmitting mirror, so as to avoid moisture affecting its sensitivity. When the incident light disappears, the electron hole pairs generated by the photon excitation will be combined, and the resistance of the photoresistor will return to its original value. When a voltage is applied to the metal electrodes at both ends of the photoresist, there will be current passing through. When exposed to light of a certain wavelength, the current will increase with the increase of light intensity, so as to realize photoelectric conversion. The photosensitive resistor has no polarity and is purely a resistance device. When used, it can be applied with both DC voltage and AC voltage. The conductivity of a semiconductor depends on the number of carriers in its conduction band.
2. Structure principle: photoresistor is a special resistor made of semiconductor materials such as vulcanized barrier or selenided barrier, and its surface is also coated with moisture-proof resin, which has photoconductive effect. The working principle of the photosensitive resistor is based on the internal photoelectric effect, that is, the electrode leads are installed at both ends of the semiconductor photosensitive material, and the photosensitive resistor is formed by packaging it in a tube shell with a transparent window.