The Relationship between Electrochemical Impedance Spectra and Photovoltaic Performance Characteristics during the Light and Thermal Ageing of Dye-Sensitized Solar Cells (original) (raw)
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Effects of aging and cyclically varying temperature on the electrical parameters of dye solar cells were analyzed with electrochemical impedance spectroscopy. Photoelectrode total resistance increased as a function of time due to increasing electron transport resistance in the TiO 2 film. On the other hand, photoelectrode recombination resistance was generally larger, electron lifetimes in the TiO 2 were film longer, and charge transfer resistance on the counter electrode was smaller after the temperature treatments than before them. These effects correlated with the slower deterioration rate of the temperature-treated cells, in comparison to the reference cells.
Impedance Spectroscopic Investigation of the Degraded Dye-Sensitized Solar Cell due to Ageing
International Journal of Photoenergy
This paper investigates the effect of ageing on the performance of dye-sensitized solar cells (DSCs). The electrical characterization of fresh and degraded DSCs is done under AM1.5G spectrum and the current density-voltage (J-V) characteristics are analyzed. Short circuit current density (JSC) decreases significantly whereas a noticeable increase in open circuit voltage is observed. These results have been further investigated electroanalytically using electrochemical impedance spectroscopy (EIS). An increase in net resistance results in a lower JSC for the degraded DSC. This decrease in current is mainly due to degradation of TiO2-dye interface, which is observed from light and dark J-V characteristics and is further confirmed by EIS measurements. A reduction in the chemical capacitance of the degraded DSC is observed, which is responsible for the shifting of Fermi level with respect to conduction band edge that further results in an increase of open circuit voltage for the degrade...
2021
In this paper DSSCs of various electrode thicknesses (L = 3 μm→12 μm) are assembled using N719 dye, an iodide (I")/triiodide (I#) redox liquid electrolyte and TiO2 (P-25) working electrode (WE). The theoretically modeled equations defining various bulk and interface impedances are incorporated with EIS spectrum analyzer software to fit the simulated EIS curves with experimentally measured EIS curves to evaluate the charger transfer and recombination properties of the assembled DSSCs. EIS fitting parameters investigated to study the impact of WE thickness on the charge transport properties of assembled DSSC. It is observed that the charger transfer resistance at TiO2/electrolyte interface (Rk) and series resistance (Rs) are reduced from 8 Ωcm2 → 4.05 Ωcm2 and 14.5 Ωcm2→10.06 Ωcm2 respectively which shows consistency with improvement in electron life time (τe) from 5.8 ms →12.4 ms for increasing WE thickness, L = 3 μm→12 μm. The combined impact of significant reduction in Rk and ...
IMPEDANCE SPECTROSCOPY AND TRANSPORT MECHANISMS OF TiO 2 - BASED DYE SENSITIZED SOLAR CELL
Photoconduction mechanism and charge dynamics in the TiO 2 -based DSSC were analyzed under dark and illumination conditions. The effects of high and low electric fields on charge dynamics in the solar cell were investigated by current-voltage characteristics. It was found that the charge dynamics of the solar cell was controlled by the thermionic emission (TEC) at lower voltage and followed by space charge limited current (SCLC) at the higher voltages. It is also observed that photoconduction mechanism is controlled by supralinear recombination mechanism while the charge dynamics is controlled by TEC and SCLC mechanisms. Spectroscopic parameters (capacitance, conductance and series resistance) at different biasing voltages and frequencies are also discussed.
Influence of TiO2 Film Thickness on the Electrochemical Behaviour of Dye-Sensitized Solar Cells
International Journal of Electrochemical Science
A commercial TiO 2 powder was deposited on F-doped SnO 2 (FTO) glass substrates by a spray coating technique with different thicknesses (6, 10 and 14 µm) to be used as photo-anode in dye-sensitized solar cells (DSSCs). N3 dye was adsorbed on each TiO 2 film for 16 h. The resulting electrodes were used to form dye-sensitized solar cells in combination with conventional electrolyte and counterelectrode. The cells were investigated by I-V characteristics and electrochemical impedance spectra. The cell formed with a TiO 2 film of 10 µm thickness reached the best performance. This thickness resulted as the best compromise in terms of absorption of incident light on the N3 dye, reduction of the recombination processes and suitable series and charge transfer resistance
Solar Energy, 2020
The present paper constitutes one of the few comprehensive studies found in literature on the stability of dyesensitized solar cells (DSSCs) under different accelerated ageing conditions. Specifically, the accelerated ageing tests involved isothermal ageing at high or low temperature, thermal shock cycling, hydrothermal ageing, and reverse biasing of conventional DSSCs, fabricated using mainly commercially available materials, prepared for DSSCs application. One-diode model was in all cases applied to the characteristic curve of the solar cells, as a simplified version of the general transmission line model used in electrochemical impedance spectroscopy, for the fast and straightforward analysis of the charge transport and back-reaction kinetics in the DSSCs. A semianalytical model (residual property model (RPM)) that was previously developed by the last author, was also applied, for the first time to solar cells, to predict the degradation of DSSCs performance due to their accelerated ageing. The results showed that moisture, in combination with high temperature, is the most critical environmental factor that leads to the degradation of DSSCs performance. In all cases of accelerated ageing, the stability of the solar cells seemed to be highly dependent on degradation/desorption phenomena of the conventional hydrophilic ruthenium (N719) dye from the TiO 2 anode. Finally, it is worth mentioning that the RPM accurately predicted the degradation of DSSCs performance in all cases of accelerated ageing. The present paper reveals a simple but powerful approach for routine evaluation and prediction of the stability of DSSCs and, hopefully, of other solar cell technologies under various accelerated ageing conditions.
ISRN Nanotechnology, 2011
The dependence of the electron density and electron lifetime in nanocrystalline-TiO2electrode on the electron back reaction withI3−in a dye-sensitized solar cell, based on a mesoporous titania (TiO2) matrix immersed in an iodine-based electrolyte, has been presented by analyzing the results of voltage decay and charge extraction measurements without modelling, without interpretation of mechanism, and without complicating calculations. This new analysis approach utilizes simple equations and basic definition of kinetics, concluding in absolute electron-density and charge-lifetime measurements. The relation of electron lifetime to open-circuit voltage indicates a peak of the long-lifetime charge at 5.5 V, which is consistent with the information of middle band suggested by Bisquert et al. (2004).
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AIP Conference Proceedings, 2019
For electricity production with zero emission Dye-sensitized solar cells (DSSC) shows a great potential having a low cost fabrication solar cell devices. In this research, we have used two types of modified titanium dioxide (TiO 2) nanoparticles as photoanodes for DSSC, such as commercial TiO 2 paste , and synthesis TiO 2 paste. These TiO 2 compact layers were coated on FTO (Fluorine doped Tin Oxide) coated conductive glass substrates using doctor blade technique. Then, a freshly prepared solution of iodide-triiodide, and Ruthenium (II) dye (N 719), were used as electrolyte and the dye, respectively. A platinum (Pt) coated FTO was used as a counter electrode. The J-V characteristics for all the devices were obtained under light evaluating their performance and to calculate the power conversion efficiency.
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Materials
The effect of TiO2 nanostructures such as nanoparticles, nanowires, nanotubes on photoanode properties, and dye-sensitized solar cells photovoltaic parameters were studied. The series of dye-sensitized solar cells based on two dyes, that is, commercially N719 and synthesized 3,7′-bis(2-cyano-1-acrylic acid)-10-ethyl-phenothiazine were tested. Additionally, the devices containing a mixture of this sensitizer and chenodeoxycholic acid as co-adsorbent were fabricated. The amount of adsorbed dye molecules to TiO2 was evaluated. The prepared photoanodes with different TiO2 nanostructures were investigated using UV-Vis spectroscopy, optical, atomic force, and scanning electron microscopes. Photovoltaic response of constructed devices was examined based on current-voltage characteristics and electrochemical impedance spectroscopy measurements. It was found that the highest UV-Vis absorption exhibited the photoanode with nanotubes addition. This indicates the highest number of sensitizer mo...
The Journal of Physical Chemistry C, 2012
The introduction of a dense TiO 2 layer between the mesoporous TiO 2 network and the charge collector in dye-sensitized solar cell anodes has been claimed to improve the performance of solar cell devices. Two mechanisms have been proposed to explain this behavior, a decrease in the electron−hole recombination at substrate/electrolyte interface and an enhancement in the electronic contact between the mesoporous TiO 2 network and the charge collecting electrode. In this work the effect of sputtered TiO 2 blocking layers (BLs) on the performance of dye-sensitized solar cells electrodes has been analyzed. It has been shown that the electron injection efficiency governed changes observed in cell efficiency. The thicker the BL, the poorer the photocurrent, and therefore, only thin BLs leaded to an increase in energy conversion efficiencies. The thickness of the BL also affected the internal series resistance of the solar cells, influencing their fill factor.