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Influence of electrolyte co-additives on the performance of dye-sensitized solar cells.

Stergiopoulos T, Rozi E, Karagianni CS, Falaras P - Nanoscale Res Lett (2011)

Bottom Line: The presence of specific chemical additives in the redox electrolyte results in an efficient increase of the photovoltaic performance of dye-sensitized solar cells (DSCs).The most effective additives are 4-tert-butylpyridine (TBP), N-methylbenzimidazole (NMBI) and guanidinium thiocyanate (GuNCS) that are adsorbed onto the photoelectrode/electrolyte interface, thus shifting the semiconductor's conduction band edge and preventing recombination with triiodides.Further addition of GuNCS in the optimized electrolytic media causes significant synergistic effects, the action of GuNCS being strongly influenced by the nature of the corresponding co-additive.

View Article: PubMed Central - HTML - PubMed

Affiliation: Institute of Physical Chemistry, NCSR "Demokritos", Aghia Paraskevi Attikis, Athens 15310, Greece. stergt@chem.demokritos.gr.

ABSTRACT
The presence of specific chemical additives in the redox electrolyte results in an efficient increase of the photovoltaic performance of dye-sensitized solar cells (DSCs). The most effective additives are 4-tert-butylpyridine (TBP), N-methylbenzimidazole (NMBI) and guanidinium thiocyanate (GuNCS) that are adsorbed onto the photoelectrode/electrolyte interface, thus shifting the semiconductor's conduction band edge and preventing recombination with triiodides. In a comparative work, we investigated in detail the action of TBP and NMBI additives in ionic liquid-based redox electrolytes with varying iodine concentrations, in order to extract the optimum additive/I2 ratio for each system. Different optimum additive/I2 ratios were determined for TBP and NMBI, despite the fact that both generally work in a similar way. Further addition of GuNCS in the optimized electrolytic media causes significant synergistic effects, the action of GuNCS being strongly influenced by the nature of the corresponding co-additive. Under the best operation conditions, power conversion efficiencies as high as 8% were obtained.

No MeSH data available.


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I-V curves for optimum DSCs (using optimum multiple layered TiO2 films) and the TBP or NMBI addition into the PMII-I2-GuNCS-PC electrolytes.
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Figure 4: I-V curves for optimum DSCs (using optimum multiple layered TiO2 films) and the TBP or NMBI addition into the PMII-I2-GuNCS-PC electrolytes.

Mentions: The above efficiencies were determined using non-optimized DSCs because we decided to stay in a system as simple as possible, in order to clearly discriminate the additive effects. Thus in a last step, we have used optimized TiO2 films electrodes (with a three layer stratification of 22 μm in total thickness, incorporating Degussa P25, scattering layer and titania nanoparticles from TiCl4 treatment) with enhanced electrooptical properties to increase the above efficiencies and find out, at the end, what is the maximum gain for a solar cell when using the two additives together in the electrolyte. From Figure 4, depicting the two I-V curves with optimum DSCs, one can infer that the electrolyte with NMBI-GuNCS gives a maximum efficiency of 5.78% (with Jsc = 13.7 mA/cm2, Voc = 762 mV and ff = 0.55). However, a much higher efficiency of 8.03%, resulting from much higher Jsc of the order of 17.5 mA/cm2 (Voc = 763 mV and ff = 0.60), is achieved when TBP and GuNCS are simultaneously incorporated inside the electrolyte. The above results are in great accordance with the optimum composition of electrolytes found in recent literature dealing with state-of-the-art cells [14]. In the case of the optimized DSCs, the much better performance of the TBP-based electrolyte (with respect to the cells using NMBI-based electrolyte) is mainly due to the particular stratification of the composite electrode. In fact, the adsorption behaviour of the TBP and NMBI additives on TiO2 could be differentiated by the small-sized titania nanoparticles (produced following the TiCl4 treatment), thus affecting in a different way the electron injection/recombination dynamics.


Influence of electrolyte co-additives on the performance of dye-sensitized solar cells.

Stergiopoulos T, Rozi E, Karagianni CS, Falaras P - Nanoscale Res Lett (2011)

I-V curves for optimum DSCs (using optimum multiple layered TiO2 films) and the TBP or NMBI addition into the PMII-I2-GuNCS-PC electrolytes.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3211393&req=5

Figure 4: I-V curves for optimum DSCs (using optimum multiple layered TiO2 films) and the TBP or NMBI addition into the PMII-I2-GuNCS-PC electrolytes.
Mentions: The above efficiencies were determined using non-optimized DSCs because we decided to stay in a system as simple as possible, in order to clearly discriminate the additive effects. Thus in a last step, we have used optimized TiO2 films electrodes (with a three layer stratification of 22 μm in total thickness, incorporating Degussa P25, scattering layer and titania nanoparticles from TiCl4 treatment) with enhanced electrooptical properties to increase the above efficiencies and find out, at the end, what is the maximum gain for a solar cell when using the two additives together in the electrolyte. From Figure 4, depicting the two I-V curves with optimum DSCs, one can infer that the electrolyte with NMBI-GuNCS gives a maximum efficiency of 5.78% (with Jsc = 13.7 mA/cm2, Voc = 762 mV and ff = 0.55). However, a much higher efficiency of 8.03%, resulting from much higher Jsc of the order of 17.5 mA/cm2 (Voc = 763 mV and ff = 0.60), is achieved when TBP and GuNCS are simultaneously incorporated inside the electrolyte. The above results are in great accordance with the optimum composition of electrolytes found in recent literature dealing with state-of-the-art cells [14]. In the case of the optimized DSCs, the much better performance of the TBP-based electrolyte (with respect to the cells using NMBI-based electrolyte) is mainly due to the particular stratification of the composite electrode. In fact, the adsorption behaviour of the TBP and NMBI additives on TiO2 could be differentiated by the small-sized titania nanoparticles (produced following the TiCl4 treatment), thus affecting in a different way the electron injection/recombination dynamics.

Bottom Line: The presence of specific chemical additives in the redox electrolyte results in an efficient increase of the photovoltaic performance of dye-sensitized solar cells (DSCs).The most effective additives are 4-tert-butylpyridine (TBP), N-methylbenzimidazole (NMBI) and guanidinium thiocyanate (GuNCS) that are adsorbed onto the photoelectrode/electrolyte interface, thus shifting the semiconductor's conduction band edge and preventing recombination with triiodides.Further addition of GuNCS in the optimized electrolytic media causes significant synergistic effects, the action of GuNCS being strongly influenced by the nature of the corresponding co-additive.

View Article: PubMed Central - HTML - PubMed

Affiliation: Institute of Physical Chemistry, NCSR "Demokritos", Aghia Paraskevi Attikis, Athens 15310, Greece. stergt@chem.demokritos.gr.

ABSTRACT
The presence of specific chemical additives in the redox electrolyte results in an efficient increase of the photovoltaic performance of dye-sensitized solar cells (DSCs). The most effective additives are 4-tert-butylpyridine (TBP), N-methylbenzimidazole (NMBI) and guanidinium thiocyanate (GuNCS) that are adsorbed onto the photoelectrode/electrolyte interface, thus shifting the semiconductor's conduction band edge and preventing recombination with triiodides. In a comparative work, we investigated in detail the action of TBP and NMBI additives in ionic liquid-based redox electrolytes with varying iodine concentrations, in order to extract the optimum additive/I2 ratio for each system. Different optimum additive/I2 ratios were determined for TBP and NMBI, despite the fact that both generally work in a similar way. Further addition of GuNCS in the optimized electrolytic media causes significant synergistic effects, the action of GuNCS being strongly influenced by the nature of the corresponding co-additive. Under the best operation conditions, power conversion efficiencies as high as 8% were obtained.

No MeSH data available.


Related in: MedlinePlus