New 3-Ethynylaryl Coumarin-Based Dyes for DSSC Applications: Synthesis, Spectroscopic Properties, and Theoretical Calculations

Abstract

A set of 3-ethynylaryl coumarin dyes with mono, bithiophenes and the fused variant, thieno [3,2-b] thiophene, as well as an alkylated benzotriazole unit were prepared and tested for dye-sensitized solar cells (DSSCs). For comparison purposes, the variation of the substitution pattern at the coumarin unit was analyzed with the natural product 6,7-dihydroxycoumarin (Esculetin) as well as 5,7-dihydroxycomarin in the case of the bithiophene dye. Crucial steps for extension of the conjugated system involved Sonogashira reaction yielding highly fluorescent molecules. Spectroscopic characterization showed that the extension of conjugation via the alkynyl bridge resulted in a strong red-shift of absorption and emission spectra (in solution) of approximately 73–79 nm and 52–89 nm, respectively, relative to 6,7-dimethoxy-4-methylcoumarin (labs = 341 nm and lem = 410 nm). Theoretical density functional theory (DFT) calculations show that the Lowest Unoccupied Molecular Orbital (LUMO) is mostly centered in the cyanoacrylic anchor unit, corroborating the high intramolecular charge transfer (ICT) character of the electronic transition. Photovoltaic performance evaluation reveals that the thieno [3,2-b] thiophene unit present in dye 8 leads to the best sensitizer of the set, with a conversion efficiency (η = 2.00%), best VOC (367 mV) and second best Jsc (9.28 mA·cm−2), surpassed only by dye 9b (Jsc = 10.19 mA·cm−2). This high photocurrent value can be attributed to increased donor ability of the 5,7-dimethoxy unit when compared to the 6,7 equivalent (9b).

Diketopyrrolopyrrole-Coumarin Conjugates for Efficient Binary Organic Solar Cells

“…Coumarin, a natural and synthetic heterocyclic compound, and their derivatives have been widely used for a range of applications such as dye-sensitized solar cells, − OSCs, − organic light-emitting diodes, and as a fluorescence emitter because of their high stability, good structural flexibility, and intrinsic high photoluminescence (PL) quantum yields . A weakly fluorescent coumarin could exhibit excellent fluorescence on proper substitution on the core with various chromophores.…”

Photocurrent and Gelation Properties of Polyphenol-Modified Titanium-Oxo Compounds

“…As one of the pharmacologically active ingredients, esculetin, a catechol derivative, has been widely used in medical aspects. , Metal complexes of esculetin can trigger cancer cell in photochemotherapeutics . As a coumarin-based chromophore also, esculetin has been used in research studies of dye-sensitized solar cells (DSSCs). , In this work, 4-methyl-esculetin (Mesc) was selected as the bisphenol ligand to modify the TOCs. Three Mesc-TOCs with different Ti nuclearities, namely, [Ti 17 O 24 (Mesc) 4 (O i Pr) 16 ] ( 1 ), [Ti 12 O 14 (O i Pr) 18 ]­[Ti 16 O 14 (Mesc) 12 (O i Pr) 14 ] ( 2 ), and [Ti 3 O­(Mesc) 2 (OAc) 2 (O i Pr) 4 ] ( 3 ), (HO i Pr = isopropanol), were prepared and structurally characterized.…”

“…25 As a coumarin-based chromophore also, esculetin has been used in research studies of dye-sensitized solar cells (DSSCs). 26,27 In this work, 4methyl-esculetin (Mesc) was selected as the bisphenol ligand to modify the TOCs. Three Mesc-TOCs with different Ti nuclearities, namely, [Ti 17 O 24 photocurrent properties of these compound-sensitized TiO 2 electrodes were evaluated.…”

Microwave-promoted Synthesis and Optoelectronic Properties of Ethoxycarbonyl-substituted Coumarin and Benzo[f]coumarin

“…Several efforts were also done to establish protocols for rational molecular design for better fluorescing coumarins, as well as benzocoumarins (Jung et al 2018). In addition, coumarins are used for other modern photonic-oriented applications such as in solar cells as dye sensitizers (Sarrato et al 2021), as organic light-emitting diode (OLED) (Genco et al 2018;Kim et al 2015), and as photo-labile materials in supramolecular assemblies (Klán et al 2013). Since its discovery also, coumarin derivatives were determined to possess a vast spectrum of bioactivities such as antiinflammatory, anticoagulant, antibacterial, antifungal, antiviral, anticancer, antihyperglycemic, and antioxidant, to name a few (Peng et al 2013;Venugopala et al 2013;Jain and Joshi 2012).…”