Transition metal complex redox shuttles for dye-sensitized solar cells

Abstract

An important link exists between the selected molecular structure of a sensitizer and the employed shuttle electrolyte to achieve high conversion efficiency in dye-sensitized solar cells (DSSCs). So far, the most commonly used redox mediator is iodide/triiodide (I − /I 3 − ), which has shown advantages such as desirable kinetic properties and high carrier collection efficiencies. However, it has several disadvantages including a low redox potential, corrosion toward metal materials and competitive blue light absorption. In this respect, the transition metal complex electrolytes represent valuable alternatives to replace with traditional I − /I 3 − couples, which can overcome the drawbacks of I − /I 3 − electrolyte. In recent years, the best efficiency of DSSC was achieved by porphyrin-sensitized solar cells with transition metal complex-based redox electrolyte. In particular, in 2014, the Gratzel group published a record DSSC efficiency of 13 % by using a new porphyrin sensitizer with Co-polypyridyl-based electrolyte. Here, we plan the engineering of structure of new transition metal complex electrolyte and the design of molecular structure of sensitizer in touch. The main focus will be held on the correlation between photophysical and electrochemical properties of the metal complex mediators and their DSSC performances. This review provides an in-depth investigation on the exciting alternative electrolyte shuttle in DSSCs and their various advantages that are endowed with both high conversion efficiency and non-corrosive properties. Fig. 11 Device stability of [Fe(CN)6] 4-/3− mediated devices during light soaking with green (stars) and blue (pentagons) light. The performance parameters a) Voc b) Jsc c) FF and d) efficiency were measured at filtered (480 nm cut off) one sun AM 1.5 light. Reproduced with permission from ref. 85.

Metal Coordination Complexes as Redox Mediators in Regenerative Dye-Sensitized Solar Cells

“…The M 0 species produced by reduction of M + at the CE back diffuses to the PE M 0 (CE) → M 0 (PE) (28) in order to participate to the oxidized dye regeneration process. The excited dye can either inject an electron into the semiconductor oxide conduction band or be deactivated to the initial dye form together with the emission of light (fluorescence) or heat: D 0 * hν or heat → D 0 (29) For efficient DSSC operation the latter process should be much slower than electron injection.…”

Robust, Scalable Synthesis of the Bulky Hagfeldt Donor for Dye‐Sensitized Solar Cells

“…DSCs have been shown to reach power conversion efficiencies (PCEs) of >14 % under 1 sun conditions and >28 % in low light, making them a cost‐effective alternative to current renewable energy sources . The tunable nature of the sensitizers in dye‐sensitized renewable energy areas, including photochemical cells, solar batteries, and DSCs, has created a large push in research efforts for sensitizer design . The prevalent donor–π bridge–acceptor (D–π–A) structure is common to all dye‐sensitized applications, as it is amenable to flexible synthetic approaches that enable the tailoring of absorption profiles.…”

μ2-Chlorido-chlorido(μ2-4-{[2-(diethylamino)ethyl]imino}pent-2-en-2-olato)bis(tetrahydrofuran-κO)cobalt(II)lithium

“…Several synthetic approaches based on organic (Sauvage, 2014), inorganic (Bergeron et al, 2005;Burschka et al, 2012;Carli et al, 2013), or organometallic compounds (Carli et al, 2016;Spokoyny et al, 2010;Sun et al, 2015;Magni et al, 2016) have been reported with [Co(bpy) 3 ] 2+/3+ and [Co(phen) 3 ] 2+/3+ (where bpy = 2,2 0 -bipyridine and phen = 1,10-phenanthroline) as redox couples. Notably, DSSCs using cobalt redox pairs mostly tether to pyridine-type ligands with complex formal charge (2+/3+) (Ben Aribia et al, 2013;Lee et al, 2015;Bella et al, 2016;Kashif et al, 2013;Pashaei et al, 2015;Giribabu et al, 2015), displaying few structural deviations mainly by varying the ligand backbone with groups of different donating/withdrawing data reports ability (Pashaei et al, 2015;Xu et al, 2013), and without nonneutral ligands in the coordination sphere.…”