Numerical Simulation of the Current−Voltage Curve in Dye-Sensitized Solar Cells

Abstract

A theoretical model based on the numerical integration of the continuity equation for electrons with traplimited density-dependent diffusion and recombination constants is implemented to describe the functioning of dye-sensitized solar cells (DSSC). The application of the model combines recent theory on charge transport in nanocrystalline materials with parameters extracted from five simple measurements: the UV/vis spectrum of the dye in solution, the steady-state current-voltage curve, the open circuit photovoltage versus light intensity curve, photocurrent transient upon switching on an illumination source, and open-circuit voltage decay upon switching off the illumination source. As a novel feature not previously included in this kind of calculations, the model includes an additional term that accounts for the charge transfer from the transparent conducting oxide (TCO) substrate to the electrolyte solution. The general applicability of the model is illustrated by applying it to two different types of cell: a TiO 2 -based solar cell with an organic solvent electrolyte and a ZnO-based solar cell with a solvent-free electrolyte. It is found that the numerical model is capable of adequately fitting all data for both systems, resulting in quantitative estimates for the main parameters controlling solar cell functioning and efficiency. The results show that it is possible to provide a global description of DSSCs based on fundamental theories for trap-limited transport and recombination using simple experimental techniques available to every solar cell laboratory. The present paper tries to help fill the gap between pure theoreticians and experimentalists working on this kind of system.

Charge collection properties of dye-sensitized solar cells based on 1-dimensional TiO2 porous nanostructures and ionic-liquid electrolytes

“…1) would not favor their adsorption into the porous electrodes. In any case the dye loading capacity of the nanocolumnar films is comparable to the best performing TiO 2 nanoparticulate films [2,53] and much larger than Fig. 2.…”

Device Physics of Dye Solar Cells

“…Physical models that predict the IV curve can be categorized as numerical [15][16][17][18][19] or analytical [20][21][22][23] models. The numerical models have the advantage that the physical principles of DSC operation can be correctly described, usually as a system of partial differential equations.…”

“…Complexity is an issue in some analytical models as well. [ 20 , 22 , 23 ] A compromise in this respect is the simple numerical model presented recently by Villanueva et al [ 19 ] The parameters of this model are estimated by adjusting them recursively to a set of steady state and dynamic measurement data. [ 19 ] However, to fi nally fi t their model to a measured solar cell IV curve, the authors use a constant series resistance as an empirical fi tting parameter in an iterative fi tting process that involves repetitive numerical solution of the model.…”

“…In this paper, we share the spirit of Villanueva et al, [ 19 ] who want to "fi ll the gap between theoreticians and experimentalists", and construct a physical DSC device model that can be verifi ed by widely available experimental techniques. In our case, we build the model around steady state parameters that can be determined by electrochemical impedance spectroscopy (EIS), optical characterization, and spectral incident-photon-tocollected-electron (IPCE) measurements in addition to photovoltaic IV characterization.…”

Effects of multilayer coating and calcination procedures on the morphology of dye-sensitized solar cell semiconductor photoelectrodes

“…They mimic plant photosynthesis, but the visible-light energy to electrical energy conversion mechanism is complex since it involves a wide variety of materials, interfaces and charge transport processes. The number of experimental variables which influence the energy conversion efficiency is very high, and some efforts have been made to identify the most significant experimental factors [8,9]. Meanwhile, experimental researchers are focused on finding cell materials and manufacturing techniques that give higher conversion efficiency and lower costs [7,[10][11][12][13].…”