Solar cells: a historic model re-evaluated
Solar or photovoltaic cells are electronic components that, assembled, form the solar panels increasingly being used by the general public.
Solar cells capture light from our star and transform its radiation or the heat generated into electricity. The theoretical maximum yield of this operation ranges between 25% and 33% depending on the materials used. Solar cells in use today, consisting of semiconductors such as silicon or perovskite, are gradually approaching the limit predicted by Shockley and Queisser in their famous 1961 article.
This model, which describes an ideal world based on simplifying assumptions, is increasingly used and cited as a reference. To make sure that comparisons of photovoltaic cell performance are reliable, scientists from the Paris-Île-de-France Photovoltaic Institute (CNRS / Chimie ParisTech / École Polytechnique / EDF / Total / Air Liquide / IPVF-SAS) and from German and Israeli laboratories set out to specify the correct conditions for the model’s use.
They identified 5 fundamental assumptions (concerning photon absorption, the collection and extraction of photogenerated charge carriers, their recombination mechanisms, and the extraction of heat generated during the conversion phenomena) which must be verified with utmost care for the predictions of the model to apply.
In this theoretical work published in Nature Photonics, the team also defined a magnitude (a figure of merit) for each identified point, quantitatively measuring the difference between a real cell and the ideal one: with this new metric, the relevant parameters can be identified on which to focus in order to improve existing solar cell systems.
Jean-Francois Guillemoles, Thomas Kirchartz, David Cahen et Uwe Rau
Guide for the Perplexed to the Shockley-Queisser Model for Solar Cells
Nature Photonics – Juillet 2019