Experiment 4 - The Photovoltaic Effect

The photovoltaic effect occurs when light shines onto the n-layer. Since this layer is thin, light can penetrate into the np-junction, where it encounters electron-hole pairs...

If the light hits an electron-hole pair, the electron and the hole are separated...

• by the positive space charge the electron is pulled into the n-layer, and
• by the negative space charge the hole is pulled into the p-layer.

Illustration photovoltaic effect. (Enlarge)

This causes a voltage of about 0.5 volts between the contacts.

To obtain, for example, a solar cell with a nominal voltage of 3 Volt, you connect internally six solar cells in series...

Illustration setup solar cell with 3 volts nominal voltage. (Enlarge)

Back to some circuits...