Question: how are solar cells made

Nicholas Pearce answered on 7 Nov 2015:

Hello,

There a several types of solar cell, the ones my research is related to are called dye-sensitised solar cells (and so I know more about these). These cells are made from layers of materials designed to trap light and extract its energy, a lot like a battery: there’s a positive end, a negative end and a liquid that conducts electricity in between.

The top layer is a glass plate coated on one side with an anode (positive electrode) like tin and then a thin white layer of titanium dioxide particles – this will not absorb light, but acts as a trap for a coloured dye molecule that does. This plate is soaked in a solution of the dye, so it sticks to the titanium particles.
A bottom layer is made of another glass plate coated on one side with a cathode (negative electrode) like platinum.
The two layers are then used to sandwich a liquid that allows electricity to conduct through it.
The dye is the bit that makes it solar powered: when light lands on the dye it is absorbed and its energy is taken by electrons than can then move around, passing them to the other layers and when electrons are moving around like this – you have electricity!

The chemistry bit is in the dye – we want colourful molecules because they absorb light, but we want ones that can use this light to shuffle the electrons in the molecule around and that’s where I come in: I try and make better dyes, that are more colourful, or that take less energy to work.