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

Institute of Physical Chemistry, NCSR "Demokritos", Aghia Paraskevi Attikis, Athens 15310, Greece. .
Nanoscale Research Letters (Impact Factor: 2.78). 04/2011; 6(1):307. DOI: 10.1186/1556-276X-6-307
Source: PubMed


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.

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    • "As an example, since TBP is expected to occupy the dye-absent TiO 2 surface, this effect is supposed to depress the reversed electron transfer from TiO 2 CB to triiodide [17]. GuSCN is also found to slow down electron recombination on account of Gu + cation adsorption on the TiO 2 surface [14] [18]. Although these additives can improve the device efficiency, their capacity and limit might be restricted by the working principle of DSSC, which is further governed by the thermodynamic and kinetic factors in essence. "
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