A comparison of 3rd generation solar cell efficiencies using thermodynamic transfer functions: Which method is best?

Exceeding the Shockley-Queisser efficiency limit for a single junction solar cell has been theorized using various means. Specifically, up- and down-conversion, carrier multiplication and intermediate band transitions have been posited as methods of improving the efficiency. Here, we compare these methods using a thermodynamic approach with a newly devised pseudo-linear system model. This method allows a schematic interpretation of the internal processes of efficiency enhancement techniques. In particular, we demonstrate that down-conversion is thermodynamically preferable to carrier multiplication, and that splitting the sun´s spectrum before impinging upon the solar cell is preferable to attempting to do this within the solar cell itself.