Correlation between Cell Performance and Physical Transport Parameters in Dye Solar Cells

The purpose of this work is to present a complete drift-diffusion model for a dye solar cells (DSCs) and to correlate numerical simulation with experimental efficiency of the cell, stressing the influence of the active layer thickness. We focus on two fundamental microscopic parameters, namely, the electron diffusion coefficient and the recombination rate constant, which are extracted by a proper simulation fitting of the experimental IV curves of four different sets of DSCs. Both the conduction band model and the multiple trapping model are considered in the fitting procedure. We show that a given set of parameters is able to fit the behavior of the cell under different illumination conditions. Conversely, parameters need to be varied to fit IV curves of cells with different TiO2 thicknesses. The calculated effective diffusion length show a dependence on the working point and on the model used to simulate the cell. This work, moreover, gives a solid numerical ground for neglecting the electronic drift component of the current.