Effects of 4-tert-butylpyridine on the quasi-Fermi levels of TiO2 films in the presence of different cations in dye-sensitized solar cells

Abstract

The effects of additives on the quasi-Fermi levels (QFL) of TiO(2) films in dye-sensitized solar cells (DSCs) were investigated by a direct method. We observed that the values of QFL of TiO(2) at short circuit and open circuit are different and found for the first time the linear relationships between QFL shifts at short circuit and open circuit induced by 4-tert-butylpyridine (TBP), and that the slopes of the lines were significantly influenced by the nature of cations in the electrolyte. Different QFL shifts at short circuit and open circuit were observed in the presence of TBA(+). These quantitative results suggest that the QFL of TiO(2) films at short circuit and open circuit can be adjusted separately by developing suitable additives and cations, which will be helpful to further improve the efficiency of DSCs.

Engineering of Osmium(II)‐Based Light Absorbers for Dye‐Sensitized Solar Cells

“…The concentration of Li + used in the present study (0.6 M ) falls between that reported for typical Ru II ‐based (0.1 M )3b and Os II ‐based DSCs (2.0 M ) 5c,d. Thus, a less positive TiO 2 conduction‐band potential can be achieved, which, in turn, could afford a higher open‐circuit photovoltage V OC , which is also ensured by the addition of 0.5 M of TBP to the electrolyte 15. Moreover, higher I − concentration (a total of 1.2 M ) in the electrolyte is expected to offset the higher electron concentration in TiO 2 and to impede the undesired recombination between electrons in TiO 2 and oxidized sensitizers 16…”

Highly efficient dye-sensitized solar cells: progress and future challenges

“…For example as discussed in Section 2.2.2, we found linear relationships between the QFL shis at short circuit and open circuit. 199 The slope of the line is equal to or less than 1 depending on the cation species in the electrolyte, as shown in Fig. 28.…”

“…The effect of TBP was also found to be inuenced by the nature of cations in the electrolyte and the QFL of the semiconductor. 199 If the QFL shi at open circuit was much larger than the shi at short circuit by developing new additives, the trade-off is possible to be eliminated and a higher efficiency is expected.…”

Interfacial engineering for dye-sensitized solar cells

“…Among these nitrogen heterocyclic compounds, 4-tert-butylpyridine (TBP) has a great advantage for improvement of the photovoltaic characteristics of DSCs by signicantly increasing the V OC of DSCs. [76][77][78][79] However, a decrease in J SC was always found to accompany with the increase of V OC . To eliminate the trade-off between V OC and J SC induced by TBP, several other kinds of nitrogen-containing heterocyclic compounds were employed as additives instead of TBP, such as pyrazole derivatives, imidazole derivatives, triazole derivatives, tetrazole derivatives, pyridine derivatives, pyrimidine derivatives, pyrazine derivatives, 1,3,5-triazine derivatives, benzimidazole derivatives, and aminothiazole derivatives.…”