Dye‐Sensitized Solar Cells with Biferrocenyl Antennae Having Quinoxaline Spacers

Enhancement of photovoltaic performance in ferrocenyl π-extended multi donor-π-acceptor (D-D'-π-A) dyes using chenodeoxycholic acid as a dye co-adsorbent for dye sensitized solar cells

A new set of multi-donor [ferrocene (D) and methoxyphenyl (D')] conjugated D-D'-π-A based dyes [Fc-(OCH3-Ph)C[double bond, length as m-dash]CH-CH[double bond, length as m-dash]CN-R{R[double bond, length as m-dash]COOH (1) and C6H4-COOH (2)}] were synthesized as sensitizers for dye-sensitized solar cell (DSSC) applications. These dyes were characterized with the aid of analytical and spectroscopic techniques such as FT-IR, HR-Mass, and 1H and 13C NMR. The thermal stability of the dyes 1 and 2 were investigated using thermogravimetric analysis (TGA) and was found to be stable around 180 °C for dye 1 and 240 °C for dye 2. The electronic absorption spectra for sensitizers display major bands between 400 and 585 nm that could be ascribed to an intramolecular charge transfer (ICT) between the electron donor and acceptor to create an efficient charge separation. The redox behaviour of the dyes was determined by cyclic voltammetry, which revealed the one-electron transfer from the ferrocene to ferrocenium ion (Fe2+ ⇌ Fe3+), and potential was utilized to determine the band gap of the dyes (2.16 eV for 1 and 2.12 eV for 2). Further, the carboxylic anchor dyes 1 and 2 have been utilized as photosensitizers in TiO2-based DSSCs with and without co-adsorbance of chenodeoxycholic acid (CDCA), and the photovoltaic performances were studied. The obtained photovoltaic parameters of dye 2 are open-circuit voltage (V oc) = 0.428 V, short-circuit current density (J sc) = 0.086 mA cm-2, the fill factor (FF) = 0.432 and the energy efficiencies (η) = 0.015%, the overall power conversion efficiencies were found to be increased in the presence of CDCA as a co-adsorbent. The photosensitizers with the addition of CDCA show higher efficiencies compared to those in the absence of CDCA, which can prevent the formation of aggregation and increased electron injection of the dyes. Among the dyes, the 4-(cyanomethyl) benzoic acid (2) anchor showed higher photovoltaic performance compared with the cyanoacrylic acid (1) anchor due to the introduction of additional π-linkers and acceptor unit, which enables the lowering of the energy barrier and charge recombination process. In addition, the experimentally observed HOMO and LUMO values were in good agreement with the theoretical calculation by the DFT-B3LYP/6-31+G**/LanL2TZf level of theory.

Copper(ii) and cobalt(iii) Schiff base complexes with hydroxy anchors as sensitizers in dye-sensitized solar cells (DSSCs)

Two Schiff base complexes of copper(ii) and cobalt(iii) having the formulae [CuL₂] (Cu-Sal) and [CoL₃] (Co-Sal) (HL = 2-(((2-hydroxyethyl)imino)methyl)phenol) have been synthesized and characterized microanalytically, spectroscopically and in the case of Cu-Sal using single crystal X-ray diffraction technique. The single crystal X-ray analysis reveals a square planar geometry around Cu(ii) satisfied by phenoxide oxygen and imine nitrogen of the L^- ligand to generate a six membered chelate ring. The solid state structure of Cu-Sal is satisfied by varied intermolecular non-covalent interactions. The nature of these interactions has been addressed with the aid of Hirshfeld surface analysis. Both compounds have been used as sensitizers in TiO₂ based dye sensitized solar cells (DSSCs) and the DSSC experiments revealed that Co-Sal offers better photovoltaic performance in comparison to Cu-Sal. The Co-Sal exhibited a J _sc of 9.75 mA cm^-2 with a V _oc of -0.648 V, incident photon to current conversion efficiency (IPCE) of 57% and η of 3.84%. The relatively better photovoltaic performance of Co-Sal could be attributed to better light absorption and dye loading than that of Cu-Sal.

Exploring Structure-Property Relationships in a Family of Ferrocene-Containing, Triphenylamine-Based Hybrid Organic Dyes

In this work, a new family of triphenylamine-based dyes equipped with ferrocene (Fc)-containing donors have been synthesized, characterized, and studied within dye-sensitized solar cells (DSSC). With the objective of designing a redox-robust iron-containing dye that effectively sensitizes titania, a family of five structurally related dyes containing ferrocene were prepared. The physicochemical properties of all dyestuffs were studied using UV-Vis and electrochemical measurements. Different cross-coupling strategies resulted in the ability to modestly tune the Fc/Fc+ redox potentials of the dye. Despite the Fc-containing dyes having optoelectronic properties consistent with the non-ferrocene parent dye, the performance of the dyes in devices was dismal and decreased with the number of appended ferrocenes. While this finding was consistent with previous attempts to explore Fc-TPA DSSC dyes, our spectroelectrochemical data supports the hypothesis that the ferrocene component of the dye is oxidized by the electrolyte, ultimately decreasing the dye’s ability to be a suitable sensitizer. While these dyes are not suitable for DSSC applications, they might find applications in other photo-induced integrated devices where charge recombination is minimal.

Y-shaped ferrocene/non-ferrocene conjugated quinoxalines for colorimetric and fluorimetric detection of picric acid

New Y-shaped ferrocene and non-ferrocene conjugated quinoxaline derivatives {[R-(CH)₂-N=CH-)₂C₁₀H₄], R = C₅H₅-Fe-C₅H₅ (1) and R = C₆H₄-OCH₃ (2)} have been synthesized and characterized using analytical and spectroscopic techniques. The thermal stability of the compounds 1 and 2 were examined by thermogravimetric analysis (TGA), both were stable up to 250 °C. The optical properties were studied using UV-Visible and fluorescence spectroscopic methods and Y-shaped ferrocene appended quinoxaline derivative 1 show a weak emission due to the quenching nature of ferrocene. The compound 2 shows enhanced fluorescence intensity in their aggregation state due to Restricted Intramolecular Rotation (RIR). Hence, the compound 2 have further utilized for the detection of picric acid (PA) by fluorimetric method and the detection limit of 1.37 × 10^-6 M was obtained. Further, paper sensor was made using compound 2 which resulted in the instant 'naked eye' response for trace detection of picric acid. Consequently, the compound 2 acts as a colorimetric sensor and can be used as a new probe for the detection of nitro aromatic explosives.

NLO-active Y-shaped ferrocene conjugated imidazole chromophores as precursors for SHG polymeric films

New Y-shaped ferrocene conjugated imidazole chromophores were prepared and fully characterized. The Y-shaped structure was confirmed by the single crystal X-ray diffraction technique. The chromophores show interesting second-order nonlinear optical (NLO) properties in solution, as determined by the Electric-Field Induced Second Harmonic generation (EFISH) technique. Remarkably, the trifluoro substituted compound 3 is characterized by a high μβEFISH value and has good potential as a molecular building block for composite films with Second Harmonic Generation (SHG) properties. For all compounds, the dipole moments and frontier orbital energies were calculated by the Density Functional Theoretical method.

Ferrocenylethenyl-substituted oxadiazoles with phenolic and nitro anchors as sensitizers in dye sensitized solar cells

Ferrocenylethenyl-substituted oxadiazoles with phenolic and nitro anchors were synthesized and used as sensitizers in dye sensitized solar cells (DSSCs).

1,1′-Bis(diphenylphosphino)ferrocene-appended nickel(ii) dithiolates as sensitizers in dye-sensitized solar cells

Herein, two dppf-appended Ni(ii) dithiolates with 2,2-diacetyl and 2-nitro anchors were prepared, and their light harvesting properties were explored in dye-sensitized solar cells (DSSCs).

Oxidatively stable ferrocenyl-π-bridge-titanocene D–π-A complexes: an electrochemical and spectroscopic investigation of the mixed-valent states

Coordination of Cu^I into ^RCp₂Ti(C₂Fc)₂ compounds results in well-separated Fe^III/II couples and mixed-valent states with distinct spectroscopic signatures.

Ferrocenyl benzimidazole with carboxylic and nitro anchors as potential sensitizers in dye-sensitized solar cells

Two ferrocenyl benzimidazoles with carboxylic and nitro anchors were prepared and their light harvesting properties explored in dye-sensitized solar cells (DSSCs).

Ferrocenyl chalcones with phenolic and pyridyl anchors as potential sensitizers in dye-sensitized solar cells

Five ferrocenyl chalcones with phenolic and pyridyl anchors were prepared and their light harvesting properties explored in dye-sensitized solar cells (DSSCs).

Ferrocene–quinoxaline Y-shaped chromophores as fascinating second-order NLO building blocks for long lasting highly active SHG polymeric films

The first example of a Y-shaped ferrocene quinoxaline derivative with high and stable SHG response in polymeric films is reported.