New 3-Ethynylaryl Coumarin-Based Dyes for DSSC Applications: Synthesis, Spectroscopic Properties, and Theoretical Calculations
A set of 3-ethynylaryl coumarin dyes with mono, bithiophenes and the fused variant, thieno [3,2-<i>b</i>] 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 patt...
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MDPI AG
2021-05-01
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| Series: | Molecules |
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| Online Access: | https://www.mdpi.com/1420-3049/26/10/2934 |
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| author | João Sarrato Ana Lucia Pinto Gabriela Malta Eva G. Röck João Pina João Carlos Lima A. Jorge Parola Paula S. Branco |
| author_facet | João Sarrato Ana Lucia Pinto Gabriela Malta Eva G. Röck João Pina João Carlos Lima A. Jorge Parola Paula S. Branco |
| author_sort | João Sarrato |
| collection | DOAJ |
| description | A set of 3-ethynylaryl coumarin dyes with mono, bithiophenes and the fused variant, thieno [3,2-<i>b</i>] 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 (λ<sub>abs</sub> = 341 nm and λ<sub>em</sub> = 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-<i>b</i>] thiophene unit present in dye <b>8</b> leads to the best sensitizer of the set, with a conversion efficiency (η = 2.00%), best V<sub>OC</sub> (367 mV) and second best J<sub>sc</sub> (9.28 mA·cm<sup>−2</sup>), surpassed only by dye <b>9b</b> (J<sub>sc</sub> = 10.19 mA·cm<sup>−2</sup>). This high photocurrent value can be attributed to increased donor ability of the 5,7-dimethoxy unit when compared to the 6,7 equivalent (<b>9b</b>). |
| first_indexed | 2024-03-10T11:23:48Z |
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| id | doaj.art-4a8302f90f134a33b2ad373e043c7a40 |
| institution | Directory Open Access Journal |
| issn | 1420-3049 |
| language | English |
| last_indexed | 2024-03-10T11:23:48Z |
| publishDate | 2021-05-01 |
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| series | Molecules |
| spelling | doaj.art-4a8302f90f134a33b2ad373e043c7a402023-11-21T19:48:55ZengMDPI AGMolecules1420-30492021-05-012610293410.3390/molecules26102934New 3-Ethynylaryl Coumarin-Based Dyes for DSSC Applications: Synthesis, Spectroscopic Properties, and Theoretical CalculationsJoão Sarrato0Ana Lucia Pinto1Gabriela Malta2Eva G. Röck3João Pina4João Carlos Lima5A. Jorge Parola6Paula S. Branco7LAQV-REQUIMTE, Departament of Chemistry, NOVA School of Science and Technology, FCT NOVA, Universidade NOVA de Lisboa, 2829-516 Caparica, PortugalLAQV-REQUIMTE, Departament of Chemistry, NOVA School of Science and Technology, FCT NOVA, Universidade NOVA de Lisboa, 2829-516 Caparica, PortugalLAQV-REQUIMTE, Departament of Chemistry, NOVA School of Science and Technology, FCT NOVA, Universidade NOVA de Lisboa, 2829-516 Caparica, PortugalDepartment of Chemistry, Coimbra Chemistry Centre, University of Coimbra, Rua Larga, 3004-535 Coimbra, PortugalDepartment of Chemistry, Coimbra Chemistry Centre, University of Coimbra, Rua Larga, 3004-535 Coimbra, PortugalLAQV-REQUIMTE, Departament of Chemistry, NOVA School of Science and Technology, FCT NOVA, Universidade NOVA de Lisboa, 2829-516 Caparica, PortugalLAQV-REQUIMTE, Departament of Chemistry, NOVA School of Science and Technology, FCT NOVA, Universidade NOVA de Lisboa, 2829-516 Caparica, PortugalLAQV-REQUIMTE, Departament of Chemistry, NOVA School of Science and Technology, FCT NOVA, Universidade NOVA de Lisboa, 2829-516 Caparica, PortugalA set of 3-ethynylaryl coumarin dyes with mono, bithiophenes and the fused variant, thieno [3,2-<i>b</i>] 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 (λ<sub>abs</sub> = 341 nm and λ<sub>em</sub> = 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-<i>b</i>] thiophene unit present in dye <b>8</b> leads to the best sensitizer of the set, with a conversion efficiency (η = 2.00%), best V<sub>OC</sub> (367 mV) and second best J<sub>sc</sub> (9.28 mA·cm<sup>−2</sup>), surpassed only by dye <b>9b</b> (J<sub>sc</sub> = 10.19 mA·cm<sup>−2</sup>). This high photocurrent value can be attributed to increased donor ability of the 5,7-dimethoxy unit when compared to the 6,7 equivalent (<b>9b</b>).https://www.mdpi.com/1420-3049/26/10/2934dye-sensitized solar cellscoumarin dyesthieno [3,2-<i>b</i>] thiophenecharge transferethynylaryl |
| spellingShingle | João Sarrato Ana Lucia Pinto Gabriela Malta Eva G. Röck João Pina João Carlos Lima A. Jorge Parola Paula S. Branco New 3-Ethynylaryl Coumarin-Based Dyes for DSSC Applications: Synthesis, Spectroscopic Properties, and Theoretical Calculations Molecules dye-sensitized solar cells coumarin dyes thieno [3,2-<i>b</i>] thiophene charge transfer ethynylaryl |
| title | New 3-Ethynylaryl Coumarin-Based Dyes for DSSC Applications: Synthesis, Spectroscopic Properties, and Theoretical Calculations |
| title_full | New 3-Ethynylaryl Coumarin-Based Dyes for DSSC Applications: Synthesis, Spectroscopic Properties, and Theoretical Calculations |
| title_fullStr | New 3-Ethynylaryl Coumarin-Based Dyes for DSSC Applications: Synthesis, Spectroscopic Properties, and Theoretical Calculations |
| title_full_unstemmed | New 3-Ethynylaryl Coumarin-Based Dyes for DSSC Applications: Synthesis, Spectroscopic Properties, and Theoretical Calculations |
| title_short | New 3-Ethynylaryl Coumarin-Based Dyes for DSSC Applications: Synthesis, Spectroscopic Properties, and Theoretical Calculations |
| title_sort | new 3 ethynylaryl coumarin based dyes for dssc applications synthesis spectroscopic properties and theoretical calculations |
| topic | dye-sensitized solar cells coumarin dyes thieno [3,2-<i>b</i>] thiophene charge transfer ethynylaryl |
| url | https://www.mdpi.com/1420-3049/26/10/2934 |
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