The Science Behind...... A Solar Battery.
To transfer light energy into electric energy.
Materials called semi-conductors, like silicon and geranium for example.
Electricity flows when light falls on the battery.
What is Going On?
The battery is made up of three very thin layers of semiconductors, respectively called:
Imagine that each of the layers has holes. In the ‘intrinsic’ layer the holes are all filled with electrons. In the ‘p’ layer there are more holes than electrons. In the ‘n’ layer there are more electrons than holes. This is the starting position.
When the battery receives light this causes an electron to jump out of the ‘intrinsic layer’ leaving a hole behind. The electron is attracted to the ‘n’ type layer by the mass of other electrons already there and forces another electron out of its hole. Into the hole left in the ‘intrinsic’ layer an electron jumps from the ’p’ layer leaving a hole. With pattern repeated more holes are left in the ‘p’ layer and more electrons in the ‘n’ layer.
As there is a ‘conductor’ running between the n and p type layers (both semiconductors) the electrons that have accumulated in the ‘n’ layer move to the holes made in the ‘p’ layer along the route of the conductor. This means that a flow of electrons from + to – has run. This process continues and now electricity continues to flow as long as the solar battery is exposed to light. This flow of electricity is often described as ‘current’.