Design, Molecular Modeling and Synthesis of Metal-Free Sensitizers of Thieno Pyridine Dyes as Light-Harvesting Materials with Efficiency Improvement Using Plasmonic Nanoparticles

Abstract

Considering the thiophene unit as an electron-rich heterocycle, it is investigated with the aim of elucidating its potential efficiency for solar cell application. With the introduction of active substituents such as COOEt, CONH 2 and CN into the thiophene segment, three novel thieno pyridine sensitizers (6a-c), based on donor-acceptor D-π-A construction, are designed and synthesized. The effect of the anchoring groups is investigated based on their molecular orbital's (MO's) energy gap (E g ). The electrostatic interaction between the synthesized dyes and metal nanoparticles, namely gold, silver and ruthenium, is believed to improve their performance as organic sensitizers. The dye-sensitized solar cells (DSSCs) are manufactured using the novel diazenyl pyridothiophene dyes, along with their metal nanoparticles conjugates as sensitizers, and were examined for efficiency improvement. Accordingly, using this modification, the photovoltaic performance was significantly improved. The promising results of conjugate (6b/AgNPs), compared with reported organic and natural sensitizers (J SC (1.136 × 10 −1 mA/cm 2 ), V OC (0.436 V), FF (0.57) and η (2.82 × 10 −2 %)), are attributed to the good interaction between the amide, methyl, amino and cyano groups attached to the thiophene pyridyl scaffolds and the surface of TiO 2 porous film. Implementation of a molecular modeling study is performed to predict the ability of the thiophene moiety to be used in solar cell applications.Molecules 2020, 25, 1813 2 of 18 the TiO 2 photoanode conduction band (i.e., the semiconductor and oxidized molecules) through the anchoring/acceptor group adsorbed on its surface (i.e., a cyano, carboxylic or phosphonic group) [6,7]. The sensitizer is illuminated by the light; thus, the excited electrons will transfer from donor to acceptor terminals through the π-conjugation bridge and then inject into the conduction band. The design and mechanism of organic sensitizers for DSSCs have been explained in detail by Obotowo et al. [8].The efficiency of a DSSC as light harvesting matter depends mainly on the nature and the amount of the adsorbed dye molecules on the photoanode [9,10] and the thickness of the photoanode as well [11]. To achieve the most optimized D-π-A dyes, they should be designed for broader absorption in the near IR region, minimizing the energy level mismatch between the oxidation potential of the dye's excited state and TiO 2 conduction band, and the HOMO and electrolyte as well, reducing the rate of charge recombination at the photoanode-electrolyte interface, prohibiting dye aggregation and increasing the stability of the DSSC [6]. Thiophene derivatives (e.g., bithiophenes [5], oligo thiophenes [5], aryl thiophenes [12] and aryl bithiophenes [13]) have attracted the attention of many researchers to synthesize donor-acceptor substituted π-conjugated systems, such as formyl π-conjugated systems, through cross-coupling/metalation followed by DMF quenching [5] and Vilsmeier-Haack-Arnold formylation reactions [13,14]. Plasmon resonance ...

Platinum Complexes from C–H Activation of Sterically Hindered [C^N] Donor Benzothiophene Imine Ligands: Synthesis and Photophysical Properties

“…The four ligands (Figure 1) utilized in this study were synthesized by condensation reactions of the appropriate amine and aldehyde. The four ligands were characterized by 1 H and 13 C NMR spectroscopy. The monometalated compounds (Figure 1) were synthesized with one equivalent of ligand per platinum center, utilizing compound [Pt 2 Me 4 (μ-SMe 2 ) 2 ], PtA, either by stirring the reactants in solution or in a microwave reactor, while bismetalated compounds (Figure 1) were synthesized with two equivalents of ligands per metal center in a solution of refluxing toluene.…”

“…K 2 PtCl 4 was purchased from the Pressure Chemical Company. NMR spectra were recorded at Bard College using Varian MR-400 MHz spectrometer ( 1 H, 400 MHz; 13 C, 100.6 MHz) and referenced to SiMe 4 ( 1 H, 13 C). Shifts are given in ppm and coupling constant J values in Hz.…”

“…The resulting solution was heated under reflux for 4 h. The solvent was removed with a rotary evaporator, and the resulting tan solid was washed with pentane and dried under vacuum. The product was characterized by 1 H NMR and 13 C NMR spectroscopy. Yield: 91% (0.46 g, 0.0015 mol).…”

“…1 H NMR (400 MHz, CDCl 3 ): δ 1.69 (d, J(H−H) = 6.7 Hz, 3H, CH 3 ), 4.64 (q, J(H−H) = 6.7 Hz, 1H, CH), {7.23−8.94 aromatics}, and 8.68 (s, 1H, CHN). 13 ]. Benzothiophene-3-carboxaldehyde (0.3093 g, 0.0019 mol) and R-(+)-1-(1-naphthyl) ethylamine (0.3264 g, 0.0019 mol) were dissolved in 30 mL of ethanol.…”

“…1 H NMR (400 MHz, CDCl 3 ): δ 1.77 (d, J(H− H) = 6.8 Hz, 3H, CH 3 ), 5.32 (q, J(H−H) = 6.8 Hz, 1H, CH), {7.23−9.02 aromatics}, and 8.69 (s, 1H, CHN). 13 )] (0.0491, 1.63 × 10 −4 mol) were dissolved in 30 mL of acetone. The resulting mixture was then allowed to stir at room temperature for 3.5 h. The solvent was removed by rotary evaporation.…”