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

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/I 2 ratio for each system. Different optimum additive/I 2 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.

Investigating the Role of I2SCN− on the Fermi Level of Electrolyte for Dye-Sensitized Solar Cells

“…This is consistent with a concurrent decrease in the diffusion coefficient of triiodide, D(I 3 À ), estimated from EIS (see Supplementary Materials), and variations in the overall solution resistance ( Table 2) [16]. This effect was more significant in the presence of Gu + in EL(GuSCN, 0.1), and it was partly attributed to the retardation of electrolyte ionic mobility in the presence of Gu + [22].…”

Review on the recent progress of carbon counter electrodes for dye-sensitized solar cells

“…As shown in Fig.2, electron injection and dye regeneration lead to the photoinduced charge separation and the lifetime is typically on a femto-to nanosecond or microsecond time scale, while the redox capture of the electron by the oxidized relay and the electron migration across the nanocrystalline TiO 2 film take place within milliseconds or even seconds [46,51]. between the electron transport and the interfacial recombination [50,52]. Generally, 5 the recombination of electrons could be found in two processes: (1) the electron in the excited-stated dye returns to its ground state; (2) the electron in TiO 2 conduction band recombines with acceptors (I ଷ ି ) in the electrolyte and excited-stated dye.…”

Developments in and prospects for photocathodic and tandem dye-sensitized solar cells

“…Nitrogen containing heterocyclic compounds have been applied in nDSCs since 1993 [164], with the most commonly used compound being tert-butylpyridine (tBP). A number of authors have reported that tBP reduces the charge recombination reactions at the electrolyte/TiO2 interface [167][168][169][170][171]. The absence of any effect on the photocathode is not necessarily an issue; in the design of complex structures, such as tandem devices the ability to optimize one electrode without significant effect on the other maybe viewed beneficially.…”