Semiconductor optoelectronic devices applications

Optoelectric devices

The devices that convert electrical energy into light and light into electrical energy through semiconductors.

Example of Optoelectric devices is Light-emitting diodes, photodiodes, and solar cells.

Light Emitting Diode (LED)

LED is a p-n junction diode that emits visible or invisible light when forward biased. The electrical energy is converted into light energy and this process is called electroluminescence.

The color of the light is determined by the energy bandgap of the material.LEDs are available in a wide range of colors such as blue (SiC), green (AlGaP) and red (GaAsP), white (GaAsP).

Application of LED

  • Indicator lamps
  • Seven segment display
  • Traffic signal


A p-n junction diode that converts the optical signal into an electric current is called a photodiode. The operation of the photodiode is exactly the opposite of LED.

Photodiode works in reverse bias. Photodiodes can generate current when the p-n junction is exposed to light and are called light sensors.

Applications of Photodiodes

  • Alarm
  • Count items in conveyor belts in industries
  • Photoconductors
  • Compact disk players
  • Smoke detectors
  • A medical application such as detector for computer tomography etc

Solar Cell

A solar cell is also called a photovoltaic cell that converts light energy into electricity or electric potential difference by the photovoltaic effect.

A solar cell is of two types- p-type and n-type. Many solar panels are connected with each other to solar arrays.

For high power applications, solar panels and solar arrays are used.

Application of Solar Cell

  • Used in calculators, watches, portable power suppliers.
  • Power supply for satellites and space modules.
  • Solar panel used to generate electricity
* * All the Notes in this blog, are referred from Tamil Nadu State Board Books and Samacheer Kalvi Books. Kindly check with the original Tamil Nadu state board books and Ncert Books.