An equivalent circuit approach to the modelling of the dynamics of dye sensitized solar cells (original) (raw)
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MODEL-BASED OPTICAL AND ELECTRICAL CHARACTERIZATION OF DYE-SENSITIZED SOLAR CELLS
2009
We present an experimentally validated coupled optical and electrical model for the dye-sensitized solar cell. The light absorption and subsequent charge generation in the photoactive layer is calculated accurately using coherent and incoherent optics. The charge generation function is then used as a source term in the electron continuity equation of the electrical model. The optical model allows to precisely analyze the reflection and absorbance losses in the individual layers. By comparing the calculated and measured quantum efficiency of a test device, one can assess the electron recombination losses at short-circuit conditions. We conclude with an integrated power loss analysis to quantify the contribution of the respective optical and electric loss mechanisms.
2016
Dye sensitized solar cells (DSSC) are used for photovoltaic applications. The paper presents a methodology for optical and electrical modeling of dye-sensitized solar cells (DSSCs). In order to take into account the scattering process, the optical model is based on the determination of the effective permittivity of the mixture and the scattering coefficient using Mie and Bruggeman theories, considering spherical particles. Then, from the radiative transfer equation, the optical generation rate of cell is deduced. Coupling the output of the optical model (the dye generation rate) to an electrical model for charge generation, transport, and first-order (linear) recombination, allows determination of current density and maximum power output. Due to our model, the dependence effects of the thickness of the photoactive layer upon the optical generation rate, the short circuit photocurrent density and the maximum power output are evidenced. Moreover, we see that when the thickness of the photoactive layer increases the optical generation rate increases. While, the short circuit current density and the maximum power output increase until d =10 µm then remain constant. Thereby, it was found that 10 µm of thickness is enough for the best I-V characteristics. Our results agree with those found in the literature. Cite This Article: El Hadji Oumar Gueye, Papa Douta Tall, Cheikh Birahim Ndao, Alle Dioum, Abdoulaye Ndiaye Dione, and Aboubaker Chedikh Beye, " An Optical and Electrical Modeling of Dye Sensitized Solar Cell:
Modeling, simulation and design of dye sensitized solar cells
RSC Adv., 2014
It is well known that recombination and transport rule the performance of dye sensitized solar cells (DSC's); although, the influence that these two phenomena have in their performance, particularly in the open circuit-potential (V oc) and in the short circuit current (J sc), is not fully understood. In this paper a phenomenological model is used to describe the quantitatively effect that transport and recombination have in the performance of the solar cell and their influence in its optimal design. The model is used to predict the influence of the recombination reaction rate constant (k r) and diffusion coefficient (D eff) in the V oc and in the J sc , whether a linear or non-linear recombination kinetic is considered. It is provided a methodology for decoupling the conduction band shifts from recombination effect in charge extraction experiments. Results also suggest that the influence of recombination in the V oc and in J sc is highly dependent on the reaction order considered. This fact highlights the importance of considering the reaction order when modeling data obtained by experimental methods. The combined results are analyzed and discussed in terms of the collection efficiency and in the optimization of the photoelectrode thickness. The model provides also a useful framework for exploring new concepts and designs for improving DSCs performance.
Phenomenological modeling of dye-sensitized solar cells under transient conditions
Solar Energy, 2011
A phenomenological model is proposed for a better understanding of the basic working mechanisms of dye-sensitized solar cells (DSCs). A steady-state approach allows the construction of the I–V characteristics, giving important informations about the main factors that influence DSCs’ performance. On the other hand, the transient approach model is an important tool to relate the phenomenological behavior with certain dynamic techniques, such as Electrochemical Impedance Spectroscopy (EIS). Bearing in mind the uncertainty arising from fitting the experimental Nyquist diagrams to general electrical analogues, this transient model contributes for a deeper understanding of the DSCs and for obtaining the relevant kinetic parameters with higher accuracy. The one-dimensional transient phenomenological model presented here assumes that the injected conduction-band electrons may recombine only with the electrolyte redox species. Due to the small dimension of the titania particles, no significant electrical potential gradient is considered, resulting only in a diffusive electron transport across the semiconductor. For modeling purposes, the mesoscopic porous structure, consisting of TiO2 nanoparticles covered with light-absorbing dye molecules and interpenetrated by the I-/I3- redox mediator (electrolyte), is considered as a homogeneous nanocrystalline structure of thickness L. The continuity and transport governing equations are defined for the mobile species involved: electrons in the TiO2 conduction band and I-/I3- ions in the electrolyte. The simulated results are in straight agreement with the experimental data.
The European Physical Journal Applied Physics, 2010
Classical electromagnetism provides limited means to model electric generators. To extend the classical theory in this respect, additional information on microscopic processes is required. In semiconductor devices and electrochemical generators such information may be obtained by modelling chemical composition. Here we use this approach for the modelling of dye-sensitised solar cells. We simulate the steady-state current-voltage characteristics of such a cell, as well as its transient response. Dynamic simulations show optoelectronic hysteresis in these cells under transient light pulse illumination. PACS. 82.47 Applied electrochemistry -72.40 Photoconduction and photovoltaic effects -73.63 Electronic transport in nanoscale materials and structures
Review on simulation of current–voltage characteristics of dye-sensitized solar cells
Journal of Industrial and Engineering Chemistry, 2019
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International Journal of Photoenergy, 2013
The steady-state current-voltage curve and dynamic response of a dye-sensitized solar cell (DSSC) is mathematically modeled based on electrical equivalent circuit. The effect of temperature and illumination on the steady-state and dynamic parameters of dye-sensitized solar cells is studied. It is found that the dynamic resistance of DSSC decreases from 619.21 Ω to 90.34 Ω with the increase in illumination level from 200 W/m 2 to 800 W/m 2 . A positive temperature coefficient of dynamic resistance is observed. The interfacial charge transfer and recombination losses at the oxide/dye/electrolyte interface are found to be the most influential factor on the overall conversion efficiency and included in the mathematical model. The saturation current of rectifying diode and saturation current of recombination diode are responsible for the transfer recombination losses and have major influence on the overall conversion efficiency.
Electrochemical Impedance Model of a (Low-cost) Dye-Sensitized Solar Cell
Chemical engineering transactions, 2014
Dye-sensitized solar cells (DSSCs) have been considered as a potential efficient tool for conversion of solar energy to electricity. DSSC's rely upon the presence of a semi-conductor (e.g. TiO2) attached to the photoanode and a sensitizer (dye) for photogeneration of electrons at the SC interface. Most efficient DSSC's are based on Ru-organic coordination complexes as sensitizer, however the finite availability of Ru led to search for other dyes, being organic molecules or other metal-coordination complexes. The efficiency of the cell can be greatly affected by recombination of generated electrons by several processes in the cell, so co-adsorbents - organic molecules - can be added to the dye to hinder recombination of the electrons by shielding the TiO2 surface. The present investigation deals with an impedance model tested for the case of a Ru-free organic sensitizer in the presence of one co-adsorbent amongst three different molecules at various concentrations. Best perfo...
Solar Energy, 2014
This study investigates the steady-state current-voltage characteristics, electronic and ionic processes and dynamic response of a TiO 2 nanoparticle based dye-sensitized solar cell (DSSC) using impedance spectroscopy and current-voltage measurements. A dye-sensitized solar cell is fabricated with 12.26 lm thick TiO 2 layer, having power conversion efficiency of 2.9% under AM1.5 spectrum with photogenerated current density (J SC ) of 7.2 mA cm À2 and open-circuit voltage (V OC ) of 672 mV. The observed electrochemical phenomenon at the TiO 2 -electrolyte interface, in diffusion of electrolyte and in charge transfer at the counter electrode is mathematically modeled using alternating current (AC) electrical equivalent circuit. The effect of temperature and illumination on the steady state and dynamic parameters of dye-sensitized solar cells is also studied. The dynamic resistance of DSSC decreases from 440.7 X to 78.6 X with increase in illumination level from 20 mW cm À2 to 100 mW cm À2 .
Modeling of interfacial and bulk charge transfer in dye-sensitized solar cells
Cogent Engineering
A simple, first-principles mathematical model has been developed to analyze the effect of interfacial and bulk charge transfer on the power output characteristics of dye-sensitized solar cells (DSSCs). Under steady state operating conditions, the Butler-Volmer equation and Schottky barrier model were applied to evaluate the voltage loss at counter electrode/electrolyte and TiO 2 /TCO interfaces, respectively. Experimental data acquired from typical DSSCs tested in our laboratory have been used to validate the theoretical J-V characteristics predicted by the present model. Compared to the conventional diffusion model, the present model fitted the experimental J-V curve more accurately at high voltages (0.65-0.8 V). Parametric studies were conducted to analyze the effect of series resistance, shunt resistance, interfacial overpotential, as well as difference between the conduction band and formal redox potentials on DSSCs' performance. Simulated results show that a "lower-limit" of shunt resistance (10 3 Ωcm 2) is necessary to guarantee a maximized efficiency. The model predicts a linear relationship between open circuit voltage (V oc) and photoanode temperature (T) with a slope of −1 mV/°C, which is close to the experimental data reported in literature. Additionally, it is observed that a small value of overpotential (2.2 mV) occurs at the short-circuit condition (J sc = 10.5 mA/cm 2), which is in a close agreement with Volmer-Butler equation. This observation suggests that,