Development of high efficiency 100% aqueous cobalt electrolyte dye-sensitised solar cells

Abstract

In this study we report the application of three cobalt redox shuttles in 100% aqueous electrolyte dye-sensitised solar cells (DSCs). By using chloride as a counter-ion for cobalt bipyridine, cobalt phenanthroline and cobalt bipyridine pyrazole, the redox shuttles were made water soluble; no surfactant or further treatment was necessary. A simple system of merely the redox shuttles and 1-methylbenzimidazole (MBI) in water as an electrolyte in combination with an organic dye and a mesoporous PEDOT counter electrode was optimised. The optimisation resulted in an average efficiency of 5.5% (record efficiency of 5.7%) at 1 sun. The results of this study present promising routes for further improvements of aqueous cobalt electrolyte DSCs.

Synthesis and Structural Analysis of Powder Complex of Tris(bipyridine)cobalt(II) Trifluoromethanesulfonate Octahydrate

“…In particular, the crystal structure of [Co(bipy)3](ClO4)2 has also been determined [4]. Quite recently the application of cobalt redox shuttle, Co(II) and Co(III) complexes of tris-bipy, to make a dye-sensitized solar cells (DSSC) electrolyte has also been developed [5].…”

First Report of Chenodeoxycholic Acid–Substituted Dyes Improving the Dye Monolayer Quality in Dye‐Sensitized Solar Cells

“…Holes were drilled with a diamond drill bit, and the glass slides were washed in an ultrasonic bath for 15 min in each of the following solutions: Hellmanex 2% detergent solution, deionized water, ethanol, and acetone. A layer of poly(3,4‐ethylenedioxythiophene) (PEDOT) was electrochemically deposited on the FTO glass from an aqueous solution of 3,4‐ethylenedioxythiophene (EDOT), as described by Ellis et al …”

“…Holes were drilled with a diamond drill bit, and the glass slides were washed in an ultrasonic bath for 15 min in each of the following solutions: Hellmanex 2% detergent solution, deionized water, ethanol, and acetone. A layer of poly(3,4-ethylenedioxythiophene) (PEDOT) was electrochemically deposited on the FTO glass from an aqueous solution of 3,4-ethylenedioxythiophene (EDOT), as described by Ellis et al [51] The solvent mixture used for the dye-staining solutions was acetonitrile/tert-butanol/tetrahydrofuran (1:1:1, v/v), with a dye concentration of 0.1 mM and various amounts of the coadsorbent CDCA, as specified in the Results and Discussion section. The staining time for all experiments was 20 h, and the electrodes were rinsed in acetonitrile and air dried in a dry box before assembly.…”

Sensitizers for Aqueous‐Based Solar Cells

“…Given the photoinstability of [Fe(CN) 6 ] 3À ,awater-soluble cobalt bipyridine ([Co(bpy) 3 ] 2 + /3 + ) complex with nitrate (NO 3 À )a st he counterion was also used for aqueous DSSCs based on MK2,a nd the efficiency reached 5.0 %( see above)w ith the addition of water-soluble polyethylene glycol. [53] Cobaltb ipyridine ([Co(bpy) 3 ] 2 + /3 + ), phenanthroline ([Co(phen) 3 ] 2 + /3 + ), and bipyridine-pyrazole ([Co(bpypz) 2 ] 2 + /3 + )c omplexes with chloride (Cl À ) as the counterion (Scheme 2) were used for aqueous DSSCs based on dye 16 (D51;S cheme 1) and gave cell efficiencies of 1.4, 4.8, and 5.7%,r espectively.T he water-soluble 4-hydroxy-2,2,6,6-tetramethyl-piperidinoxyl redox couple (TEMPOL/ TEMPOL + ,S cheme 2), [54] with ar edox potential approximately 0.3 Vm ore positivet han that of the I À /I 3 À couple, was used for aqueous DSSCs based on dye 17 (D205;Scheme 1). [31] The cobalt-based DSSC wasa lso found to be more stable than the [Fe(CN) 6 ] 4À/3À -basedD SSC, as shown in Figure 10.…”

“…100 %a queous cobalte lectrolytes. [53] Cobaltb ipyridine ([Co(bpy) 3 ] 2 + /3 + ), phenanthroline ([Co(phen) 3 ] 2 + /3 + ), and bipyridine-pyrazole ([Co(bpypz) 2 ] 2 + /3 + )c omplexes with chloride (Cl À ) as the counterion (Scheme 2) were used for aqueous DSSCs based on dye 16 (D51;S cheme 1) and gave cell efficiencies of 1.4, 4.8, and 5.7%,r espectively.T he water-soluble 4-hydroxy-2,2,6,6-tetramethyl-piperidinoxyl redox couple (TEMPOL/ TEMPOL + ,S cheme 2), [54] with ar edox potential approximately 0.3 Vm ore positivet han that of the I À /I 3 À couple, was used for aqueous DSSCs based on dye 17 (D205;Scheme 1).…”