Solar cell structure, working principle, Tübingen University
Solar cell structure, working principle, Tübingen University

Structure of a solar cells - function and working principle

 

Solar cells are structured in layers with different functions. The working principle is the same as in semiconductors.

 

The main part of a silicon (Si) solar cell generating solar power is formed by two differently doped (n- and p-) silicon layers. A physical barrier is created between them along the p-/n- junction, with electrons and holes diffusing into regions of lower concentration.

 

This depleted region or space charge region can only be overcome with the help of photons i.e. sunlight.

 

To be able to channel electrones and holes and generate electric power, metal contacts need to be printed onto the front and rear side. Generally, a full aluminium or silver layer is screenprinted onto the rear. A thin grid forms the front contact keeping the impact on light entering the silicon cells as low as possible.

 

To reduce light reflection, a thin film of silicon nitride or titanium dioxide is coated onto the surface.