High photo-currents with a zwitterionic thiocyanate-free dye in aqueous-based dye sensitized solar cells

Abstract

We report a new water soluble and stable thiolate/disulfide redox couple (T(-)/DS) and its use with a new zwitterionic and thiocyanate-free dye (T169) in a 100% aqueous electrolyte system. A DSSC incorporating T169 and the T(-)/DS showed the highest photocurrents (Jsc = 13.30 mA cm(-2)) and IPCE% (84%) values reported to date. In addition, a 2000 h long-term stability measurement was performed, where Jsc and Voc of the above mentioned DSSC stayed somehow the same except for the fill factor (FF) which decreased from 0.62 to 0.48 and consequently lowered the total efficiency (from η = 4.5% on day 1 to η = 3.3% after 2000 h).

Sensitizers for Aqueous‐Based Solar Cells

“…The TEMPO/TEMPO + couple( Scheme2)w as also reported recently for aD SSCw ithd ye 18 (LEG4; Scheme 1) as the sensitizer. [57] When the T À /DS redox couple (Scheme 2) were used with ruthenium dyes (Scheme 1), such as dye 20 (C106)a nd 21 (T169), relatively high photocurrents (J SC )o fu pt o1 0.0 and 13.0 mA cm À2 were obtained, respectively,c ompared with those of the other aqueous DSSCs. Surprisingly,a ddition of as urfactant( sodium dodecyl sulfate) resultedi nl ower cell performance.…”

“…[55] The cell had an average efficiency of 4.14 %a nd an impressively high photovoltage of 955 mV. [57] It is worth noting that the redox couple in water is considerably more stable than that in acetonitrile. Water-soluble, weakly light absorbing, and noncorrosive thiolate/disulfide mediators were developed for 100 %a queous DSSCs duet ot he inclusion of aw ater-soluble counterparto re ntity.S un et al introduced ai midazolium salt to form 1-ethyl-3-methylimidazolium 4methyl-1,2,4-triazole-3-thiolate (TT À EMI + )a nd its dimer 3,3'-dithiobis[4-methyl-(1,2,4)-triazole] (DTT).…”

“…[56] Ghaddar et al appliedathiolate/ disulfidec ouple with ah ydrophilic hydroxyethyl entity,t hat is, 1-(2-hydroxyethyl)-5-mercaptotetrazole potassium salt (T À )a nd its disulfide dimer (DS). [57] When the T À /DS redox couple (Scheme 2) were used with ruthenium dyes (Scheme 1), such as dye 20 (C106)a nd 21 (T169), relatively high photocurrents (J SC )o fu pt o1 0.0 and 13.0 mA cm À2 were obtained, respectively,c ompared with those of the other aqueous DSSCs. Compared with the hydrophobic C106 dye (3.17 %), application of the amphiphilic T169 dye as the zwitterion not only provided ab etter cell efficiency of 4.5% but also superiorl ong-term stability (i.e.,7 5% of the initial cell efficiencyw as retained after 2000 h).…”

“…Compared with the hydrophobic C106 dye (3.17 %), application of the amphiphilic T169 dye as the zwitterion not only provided ab etter cell efficiency of 4.5% but also superiorl ong-term stability (i.e.,7 5% of the initial cell efficiencyw as retained after 2000 h). [57] It is worth noting that the redox couple in water is considerably more stable than that in acetonitrile. Quasi-solid electrolytes are out of the scope of this review,a nd some discussions have been covered in ar ecent review.…”

Cobalt-Based Electrolytes for Dye-Sensitized Solar Cells: Recent Advances towards Stable Devices

“…On the other hand, water as the most abundant and benign solvent on Earth and is ideal for the preparation of DSC electrolytes; several research groups have recently turned their interest toward this direction [55,70,[90][91][92][93][94]. Another drawback, typical of quasi-solid DSCs, concerns the effect of the poor penetration of gel electrolytes into the mesoporous photoanodes [95].…”