Sarrato João, Pinto Ana Lucia, Malta Gabriela, Röck Eva G, Pina João, Lima João Carlos, Parola A Jorge, Branco Paula S
LAQV-REQUIMTE, Departament of Chemistry, NOVA School of Science and Technology, FCT NOVA, Universidade NOVA de Lisboa, 2829-516 Caparica, Portugal.
Department of Chemistry, Coimbra Chemistry Centre, University of Coimbra, Rua Larga, 3004-535 Coimbra, Portugal.
Molecules. 2021 May 14;26(10):2934. doi: 10.3390/molecules26102934.
A set of 3-ethynylaryl coumarin dyes with mono, bithiophenes and the fused variant, thieno [3,2-] 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 = 341 nm and λ = 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-] thiophene unit present in dye leads to the best sensitizer of the set, with a conversion efficiency (η = 2.00%), best V (367 mV) and second best J (9.28 mA·cm), surpassed only by dye (J = 10.19 mA·cm). This high photocurrent value can be attributed to increased donor ability of the 5,7-dimethoxy unit when compared to the 6,7 equivalent ().
制备了一组含有单噻吩、双噻吩以及稠合变体噻吩并[3,2 -]噻吩的3 - 乙炔基芳基香豆素染料，以及一个烷基化苯并三唑单元，并对其进行了染料敏化太阳能电池（DSSC）测试。为了进行比较，以天然产物6,7 - 二羟基香豆素（七叶亭）以及在双噻吩染料情况下的5,7 - 二羟基香豆素分析了香豆素单元取代模式的变化。共轭体系扩展的关键步骤涉及Sonogashira反应，生成高荧光分子。光谱表征表明，通过炔基桥扩展共轭导致吸收光谱和发射光谱（在溶液中）相对于6,7 - 二甲氧基 - 4 - 甲基香豆素（λ = 341 nm和λ = 410 nm）分别发生约73 - 79 nm和52 - 89 nm的强烈红移。理论密度泛函理论（DFT）计算表明，最低未占分子轨道（LUMO）主要集中在氰基丙烯酸锚定单元中，证实了电子跃迁的高分子内电荷转移（ICT）特性。光伏性能评估表明，染料中存在的噻吩并[3,2 -]噻吩单元导致该组中最佳的敏化剂，具有转换效率（η = 2.00%）、最佳的V（367 mV）和第二好的J（9.28 mA·cm），仅被染料（J = 10.19 mA·cm）超过。与6, ,7 - 二羟基香豆素相比，这种高光电流值可归因于5,7 - 二甲氧基单元供体能力的增强。
