When a suitable light falling on a PN junction produces a potential dfferenec
across it. This voltage is capable of driving a current through an external circuit, this phenomenon is called the Photovoltaic Effect.
This photovoltaic effect was first invented by E. Bequerel in 1839. He found that
certain materials would produce very small amount of electric current when it is exposed to light.
On continuous effort Bell laboratories in 1954 constructed a first photo-voltaic cell.
Due to the energy crisis photovoltaic technology is becoming a main source of electrical power for many industrial and domestic applications.
In this, consideration a device is so constructed in which solar energy is
converted into electrical energy. Therefore this device is called as photovoltaic cell or solar cell.
In the solar cell semiconductor material is
used, when light energy falling on it electrons from the semiconductor
material are get free from the atom in the semiconductor. Further these free
electrons are made free to move through the semiconductor by applying
external potential or voltage. Finally due to this arrangement electric
current observed in the electrical circuit. The current produced is found to
be directly depends up on light intensity falling on the semiconductor
materials.
