D鈥揇鈭捪€鈥揂-Type Organic Dyes for Dye-Sensitized Solar Cells with a Potential for Direct Electron Injection and a High Extinction Coefficient: Synthesis, Characterization, and Theoretical Investigation

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• 作者：Supawadee Namuangruk ; Ryoichi Fukuda ; Masahiro Ehara ; Jittima Meeprasert ; Tanika Khanasa ; Somphob Morada ; Tinnagon Kaewin ; Siriporn Jungsuttiwong ; Taweesak Sudyoadsuk ; Vinich Promarak
• 刊名：The Journal of Physical Chemistry C
• 出版年：2012
• 出版时间：December 13, 2012
• 年：2012
• 卷：116
• 期：49
• 页码：25653-25663
• 全文大小：446K
• 年卷期：v.116,no.49(December 13, 2012)
• ISSN：1932-7455

文摘

A series of organic sensitizers with the direct electron injection mechanism and a high molar extinction coefficient comprising double donors, a 蟺-spacer, and anchoring acceptor groups (D鈥揇鈭捪€鈥揂 type) were synthesized and characterized by experimental and theoretical methods for dye-sensitized solar cells. (E)-2-Cyano-3-(5鈥?(4-((4-(3,6-di-tert-butylcarbazol-9-yl)phenyl)dodecylamino)phenyl)-[2,2鈥?5鈥?2鈥?terthiophene]-5-yl)acrylic acid showed performance with a maximal incident photon to electron conversion efficiency of 83%, J_sc value of 10.89 mA cm^鈥?, V_oc value of 0.70 V, and fill factor of 0.67, which correspond to an overall conversion efficiency of 5.12% under AM 1.5G illumination. The molecular geometry, electronic structure, and excited states were investigated with density functional theory, time-dependent density functional theory, and the symmetry-adapted cluster-configuration interaction method. The double donor moieties not only contribute to enhancement of the electron-donating ability, but also inhibit aggregation between dye molecules and prevent iodide/triiodide in the electrolyte from recombining with injected electrons in TiO₂. Detailed assignments of the UV鈥搗is spectra below the ionization threshold are given. The low-lying light-harvesting state has intramolecular charge transfer character with a high molar extinction coefficient because of the long 蟺-spacer. Our experimental and theoretical findings support the potential of direct electron injection from the dye to TiO₂ in one step with electronic excitation for the present D鈥揇鈭捪€鈥揂 sensitizers. The direct electron injection, inhibited aggregation, and high molar extinction coefficient may be the origin of the observed high efficiency. This type of D鈥揇鈭捪€鈥揂 structure with direct electron injection would simplify the strategy for designing organic sensitizers.