What makes a good solar cell?

The following chapter provides some useful indicators,

Thank you Mr Mohamed EL-Shimy

With pleasure!

Dear Billel Rezini:

The selection of the best suitable material for thin film's solar cells depends on the layer you pursuit to enhance,

For the different layers of the solar cell, different properties are looked to be enhanced.

For example, for the Window layer... this should be a relative large bandgap material (without being an insulator) e.g. CdS, CdSe(n-type) or ZnS are some of the common and conventional materials used for this purpose.

For the Absorber, this one should be a small bandgap material (again, without being in the limit of a degenerate semiconductor).

Sometimes, the same layer can do the function of the Window layer and the n-type layer at the same time.

Is important to remind that the material chosen for the Electrodes must be (in addition to be a conducting material, like a metal) able to form a good Schottky Union between the Contact and the Buffer/Window layer, which normally are semiconductor materials. The Contacts also must be chemically stable to avoid the formation of oxides and avoid diffusion to the interior of the material.

One nice tip is: Avoid the use of Ag as the material for the contacts, you can use Al for your proofs of concept and experimental junctions. Then if you can have access to gold, you can make gold contacts for purpose of scientific publications or/and to proof the applicability of your device.

Another tip (this one could seem more obvious, but I think is worth to mention):

If you are going to deposit Al for your Contacts, do it at ambient temperature, to avoid the formation of a thin layer of Al2O3 (unless you have the option to grow it in a vacuum atmosphere).

Another separate layer for electronic passivation can be used to enhance the electronic defects passivation at the interface between the Contacts and the above (or below) placed layer (however this layer is most used for the rear contact passivation). If you are going to include this layer on the solar cell, the material considered for it should be a n-type or p-type medium bandgap, "transparernt" and conducting semiconductor, as a dielectric (ZnO, HfO2, TiO2, to mention a few). with a thickness between 1 and 5 nm.

Each aspect of each of the solar cells layers should be studied with specialized techniques, aiming to enhance each of the functions you need in a solar cell, as: Charge Transport, Diffusion Barrier, Thermal and Chemical Stability, Density of Defects, etc...

So, each aspect of the global performance of the solar cell drives a specific study of a particular set of properties; optical, electric, chemical or structural.

Such an interesting topic, thank you !

Regards !

Thank you Mr Franklin Uriel Parás Hernández

Check the following books:

Wenham, Stuart R., Martin A. Green, Muriel E. Watt, Richard Corkish, and Alistair Sproul. Applied photovoltaics. Routledge, 2013.

Archer, Mary D., and Martin A. Green, eds. Clean electricity from photovoltaics. Vol. 1. London: Imperial College Press, 2001.

You mean the system or the solar cell ?