Photoconductor

Definition

A photoconductor is a material whose electrical conductivity increases when exposed to light. It is used in various applications where the control of electric current by light is essential.

5 Must Know Facts For Your Next Test

1. Photoconductors are key components in devices like photocopiers and optical sensors.
2. The increase in conductivity occurs because photons excite electrons from the valence band to the conduction band.
3. Common materials used as photoconductors include selenium, lead sulfide, and cadmium sulfide.
4. The efficiency of a photoconductor depends on its ability to absorb light and generate charge carriers.
5. In the absence of light, photoconductors have low electrical conductivity.

Review Questions

• What happens to the electrical conductivity of a photoconductor when it is exposed to light?
• Name at least two common materials that are used as photoconductors.
• How do photons affect the electrons in a photoconductor?

Related terms

Valence Band: The energy band in a solid where electrons are present just before they gain enough energy to jump into the conduction band.

Conduction Band: The range of electron energies higher than those of the valence band, where free electrons can increase electrical conductivity.

Photoelectric Effect: The emission of electrons or other free carriers when light shines on a material.