Ferrocene Derivatives Functionalized with Donor/Acceptor (Hetero)Aromatic Substituents: Tuning of Redox Properties

Abstract

A series of functionalized ferrocene derivatives carrying electron-donor and electron-withdrawing (hetero)aromatic substituents has been designed as potential alternative electrolyte redox couples for dye-sensitized solar cells (DSSC). The compounds have been synthesized and fully characterized in their optical and electrochemical properties. A general synthetic approach that implies the use of a microwave assisted Suzuki coupling has been developed to access a significative number of compounds. The presence of different electron-rich and electron-poor substituents provided fine tuning of optical properties and energy levels. HOMO and LUMO energy values showed that the substitution of one or two cyclopentadienyl rings of ferrocene can be successfully exploited to increase the maximum attainable voltage from a standard DSSC device using TiO2 as a semiconductor, opening the way to highly efficient, non-toxic, and cheap redox shuttles to be employed in solar energy technologies.

Recent advances on ferrocene-based photoinitiating systems

“…Considering its low oxidation potential, ferrocene is also an excellent electron-donating group so that numerous push-pull dyes were designed with this iron (II) complex. [173][174][175][176][177][178][179][180] This metallocene which is a cheap compound is also characterized by a low toxicity so that this complex is an ideal candidate for the design of photoinitiators. [181][182][183][184][185][186][187] Compared to the aforementioned dyes, ferrocene-based photoinitiating systems exhibit advantages and disadvantages that are listed in the Table 1.…”

Theory for Heterogeneous Electron Transfer Kinetics on Nanocorrugated Atomic Stepped Metal Electrodes

“…Physical parameters are φ E 0 = 5.93 eV (Pt(111), a = 0.392 nm, E F = 9.74 eV and n 0 = 13.8 × 10 22 cm –3 for Pt metal. r d = 0.137 nm, μ = 1.85 D and δ̃ = −0.04 for H 2 O. r i = 0.604 nm, E HOMO = 7.1 eV for [Fe­(H 2 O) 6 ] 2+/3+ and E LUMO = 3.59 eV for [Ru­(NH 3 ) 6 ] 2+/3+ . , …”

Bio and non‐bio materials‐based quasi‐solid state electrolytes in DSSC : A review

“…The illustration of operation principles in terms of electron flow in the DSSC is shown in Figure 1. Besides, these are other types of electrolyte such as transition metal‐based complexes ([Co(bpy‐pz) 2 ] 2+/3+ , CuI/II(tmby) 2 , [Ni(carbollide) 2 ] −/0 , Fe(bpy) 3 3+/2+ , ferrocenylthiophene) 43‐46 and also carbon‐based redox‐active molecules (hydroquinone, guanidine, quinoxaline) 47‐49 . The benefit of using these non‐iodide‐based electrolytes allows the DSSC to operate at a higher potential window up to 1.4 V 45,50 …”

“…The I À molecule will then move towards the cathode side to undergo reduction to regenerate the I 3 À molecule. 42 The illustration of operation principles in terms of electron flow in the DSSC is shown in Figure , ferrocenylthiophene) [43][44][45][46] and also carbon-based redox-active molecules (hydroquinone, guanidine, quinoxaline). [47][48][49] The benefit of using these non-iodide-based electrolytes allows the DSSC to operate at a higher potential window up to 1.4 V. 45,50 The Nasar group developed the fifth-generation polyurethane dendrimer end-capped with 2,2,6,6-tetrame thylpiperidin-1-oxyl (TEMPO), which can partially reduce the amount of liquid I À /I 3 À solution.…”