First application of bis(oxalate)borate ionic liquids (ILBOBs) in high-performance dye-sensitized solar cells

Abstract

A series of bis(oxalate)borate ionic liquids (ILBOBs) were developed for the first time as the necessary components of the electrolyte system for dye-sensitized solar cells (DSCs). It was found that the photovoltaic performances of DSCs were significantly improved by 26% to 45% with these ILBOBs in the organic solvent electrolytes. Systematic investigations were carried out to reveal the effects of the chain lengths of the quaternary ammonium BOB as well as the cations of the ILBOBs on the performances of the DSCs. Among them, the highest power conversion efficiency (PCE) was achieved by the DSC based on the electrolyte containing 1-ethyl-3-methylimidazolium bis(oxalate)borate (EmimBOB). Specifically, the addition of EmimBOB increased the short circuit current densities (J sc ) from 11.87 mA cm 22 to 15.99 mA cm 22, and the open-circuit voltage (V oc ) from 0.721 V to 0.742 V, accompanied by a final 45% improvement of the overall PCE from 6.01% to 8.73% under AM 1.5, 100 mW cm 22 illumination. As an ionic liquid, EmimBOB was also used to develop a solvent-free electrolyte system. Compared with the one containing pure 1-methyl-3-propylimidazolium iodide (PMII), the hybrid solvent-free electrolyte system based on the EmimBOB/PMII combination notably increased the PCE of the DSCs from 3.48% to 5.38%.Finally, using solvent-free electrolytes, the long-term stability of the DSC devices were remarkably improved.

Ionic liquid-based green processes for energy production

“…Another series of bis(oxalate)borate-based ILs (ILBOBs, Fig. 32) were introduced into the electrolyte system of a DSC as additives by Wang et al 206 The photovoltaic performance of the corresponding devices were improved from 26% to 45% in acetonitrile electrolytes compared with the non-additive one, in which the highest efficiency of 8.73% was obtained for On the other hand, the organic thiolate/disulfide redox couple [EMIM][McMT]/BMT (Fig. 32) was also developed.…”

Effects of triphenyl phosphate as an inexpensive additive on the photovoltaic performance of dye-sensitized nanocrystalline TiO2 solar cells

“…24,29 Since 4-tert-butylpyridine (TBP) was used as additive for iodide/triiodide electrolyte, during the last years, various efforts have been intensively paid to apply some functional organic compounds as additives into the electrolyte systems. [31][32][33][34][35] Recently, tributyl phosphate (TBPP) has been introduced as efficient additive for iodide/triiodide system to modify the dye/TiO 2 /electrolyte interface. 36 In this paper, we have focused on the study of the effects of triphenyl phosphate (TPP) in the iodide/triiodide electrolyte, as another phosphate additive, using two different dyes (2-cyano-3-(4-(diphenylamino)phenyl)acrylic acid (TPA) and N719) on the DSSC performance.…”

Supramolecular Ionic Liquid Gels for Quasi-Solid-State Dye-Sensitized Solar Cells

“…Ionic liquids (ILs) are room temperature molten salts with negligible vapor pressure, high thermal stability and ionic conductivity, and the ability to dissolve organic and inorganic solutes as well as tunable solvent properties. − They have been widely used to replace traditional volatile organic solvents in DSSCs due to their low volatility and high ionic conductivity. − However, devices based on room temperature IL electrolytes are still demonstrating leakage problems in practical use. , …”