I was reading a paper that performed simulation of a solar cell under illuminated conditions. Obviously, in these conditions, the device is out of thermodynamic equilibrium. For example the distribution of charges can clearly not be computed by a Boltzmann distribution.
However, as one of their boundary conditions, they use the hypothesis that the electrodes are indeed in equilibrium (unlike the rest of the device). Using notions of schottky contact, and equilibrium distribution laws, this allows them to derive a boundary condition for the charge concentration at the electrodes.
However, I don't understand the physical meaning of this. what is the physical motivation fot the assumption that the electrodes of a working device are in equilibrium ?
Here is a link to the paper (I think it is in public access). You can find mention of this assumption on page 3/9, end of the first column: https://www.researchgate.net/publication/313875095_Improving_Perovskite_Solar_Cells_Insights_From_a_Validated_Device_Model
N.B: it does not seem to be a common assumption. Other authors might choose other variants for boundary conditions