Theoretical modelling of the electrode thickness effect on maximum power point of dye‐sensitized solar cell

Abstract

The maximum power point (MPP) of a dye‐sensitized solar cell (DSSC) is often more important than the open‐circuit voltage and the short‐circuit current as MPP better represents the DSSC power output and energy conversion efficiency. In this investigation, the DSSC J–V characteristics and MPP were studied using a simple theoretical electron diffusion model. Parametric analyses were performed to determine the particular effect of electrode thickness on the MPP output. The analytical results are well consistent with the experimental results published in the literature. In the optimization analysis, it was specially found that the optimal electrode thickness for the highest MPP is rather insensitive to the operating conditions. It implies that an optimally designed DSSC can be always operated at its highest MPP regardless of any geographical, seasonal, and solar hour factors. Such an important attribute facilitates the design and manufacture of DSSC for worldwide commercialization at competitive costs.

Influence of pore structure on ion diffusion property in porous TiO2 coating and photovoltaic performance of dye-sensitized solar cells

“…Consequently, the charge recombination between the conduction-band electrons and the I 3 − ions is lowered, which leads to the increase in the open circuit voltage. Compared with the reported optimal coating thickness of 10-20 μm [28][29][30][31][32][33][34][35][36], the optimal coating thickness was interestingly found to reach a high level of~30 μm. This is attributed to the larger limiting current densities for 30 μm thick coatings owing to the higher ion diffusion coefficient in the porous coating with bimodal-sized pores.…”

“…As a result, the thickened electrode can absorb more photons and contribute to an increased short circuit current density. However, since most of the irradiation is efficiently absorbed by the former part of the coating, and the contribution of the latter part of the coating with a higher thickness to the electron generation becomes less [28][29][30][31][32]. Therefore, the short circuit current density will reach a saturation level with the increase in the coating thickness.…”

“…On the other hand, the increase in the coating thickness causes more recombination sites, which exist on the TiO 2 particle surface within the photoanode. The charge recombination between electrons in the TiO 2 conduction-band and the I 3 − electrolyte ions becomes more and more serious with the increase in the coating thickness [28][29][30][31][32]. Consequently, a decrease in the short circuit current density is expected.…”

“…For a given pore structure, the increase in the coating thickness leads to the increase in the total internal surface area and dye loading [28][29][30][31][32]. As a result, the thickened electrode can absorb more photons and contribute to an increased short circuit current density.…”

Exact Analytical Analysis of Dye-Sensitized Solar Cell: Improved Method and Comparative Study

“…Thickness dependence can be explained by electron dilution effect. As depth of electrode increases, the absorption of intensity decreases resulting in decrease in charge density and hence V oc [26].…”