Tailoring the Optical Properties of Organic D-pi-A Photosensitizers: Effect of Sulfur Introduction in the Acceptor Group

Year: 2019

Authors: Ottavia Bettucci, Daniele Franchi, Adalgisa Sinicropi, Mariangela di Donato, Paolo Foggi, Fabrizia Fabrizi de Biani, Gianna Reginato, Lorenzo Zani, Massimo Calamante, Alessandro Mordini

Autors Affiliation: Department of Biotechnology, Chemistry and Pharmacy, University of Siena, Via A. Moro 2, 53100 Siena, Italy Institute of Chemistry of Organometallic Compounds (CNR-ICCOM), Via Madonna del Piano 10, 50019 Sesto Fiorentino, Italy European Laboratory for Non-linear Spectroscopy (LENS), Via N. Carrara 1, 50019 Sesto Fiorentino, Italy National Institute of Optics (CNR-INO), Largo E. Fermi 6, 50125 Florence, Italy Department of Chemistry \”U. Schiff\”, University of Florence, Via della Lastruccia 13, 50019 Sesto Fiorentino, Italy CSGI, Consorzio per lo Sviluppo dei Sistemi a Grande Interfase, Via della Lastruccia 3, 50019, Sesto Fiorentino, Italy Department of Chemistry, University of Perugia, Via Elce di Sotto 8, 06123 Perugia, Italy

Abstract: In this work, we present for the first time the synthesis and characterization of potential DSSC organic sensitizers whose cyanoacrylic acceptor/anchoring group was modified by replacement of oxygen with one or more sulfur atoms. Using known carboxylic acid dye DF15 as a reference, their TD-DFT computational analysis indicated that oxygen-sulfur substitution should induce a significant red-shift of the corresponding UV/Vis absorption spectra. Whereas synthesis of monothio-carboxylic derivatives of DF15 was successfully carried out, isolation of the analogous dithiocarboxylic acid proved impossible due to its very low stability: despite that, their relative spectroscopic properties could be compared by analyzing the corresponding benzylic esters. Combined computational and transient absorption spectroscopy studies suggested that photoexcited thiocarboxylic acid 1-SO and thioamide 1-SN were able to inject electrons into nanocrystalline TiO2 and indicated a similar charge injection efficiency for 1-SO relative to DF15. Preliminary DSSC studies showed that, when tert-butylpyridine was present in the electrolyte solution, 1-SO was rapidly degraded; however, in the absence of basic additives 1-SO provided a sufficiently stable device, giving a slightly lower efficiency compared to carboxylic sensitizer DF15.


Volume: 2019 (4)      Pages from: 812  to: 825

More Information: We thank \”Cassa di Risparmio di Firenze\” Foundation (\”ENERGYLAB\” Project, 2016-2018), Regione Toscana (\”ENCOLOR Design\” Project, 2017-2019) and the European Union Horizon 2020 Research and Innovation Programme (grant agreement: \”Laserlab-Europe\”, H2020 EC-GA 654148) for financial support. We also thank Carlo Bartoli for his helpful support in the solar cells construction. A. S. thanks CINECA and C.R.E.A. (Colle Val D\’Elsa, Siena, Italy) for the availability of high-performance computing resources and M.I.U.R. Grant – Department of Excellence 2018-2022.
KeyWords: Organosulfur compounds, Thiocarboxylic acid, Thioamide, Transient absorption spectroscopy, Dye‐sensitized solar cells
DOI: 10.1002/ejoc.201801497

Citations: 2
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