N-Aryl stilbazolium dyes as sensitizers for solar cells

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• 作者：Octavia A. Blackburn^a ; Benjamin J. Coe^a ; ^{b.coe@manchester.ac.uk"" rel=""nofollow} ; Valentine Hahn^a ; Madeleine Helliwell^a ; James Raftery^a ; Yien T. Ta^a ; Laurence M. Peter^b ; Hongxia Wang^b ; Juan A. Anta^c ; Elena Guillé ; n^c
• 关键词：Stilbazolium salts ; Dye sensitizers ; Solar cells ; UV-visible absorption spectroscopy ; Electrochemistry ; Density functional theory
• 刊名：Dyes and Pigments
• 出版年：2012
• 出版时间：January 2012
• 年：2012
• 卷：92
• 期：1
• 页码：766-777
• 全文大小：1105 K

文摘

Eight new N-arylstilbazolium chromophores with electron donating –NR₂ (R = Me or Ph) substituents have been synthesized via Knoevenagel condensations and isolated as their PF₆⁻ salts. These compounds have been characterized by using various techniques including ¹H NMR and IR spectroscopies and electrospray mass spectrometry. UV–vis absorption spectra recorded in acetonitrile are dominated by intense, low energy π → π* intramolecular charge-transfer (ICT) bands, and replacing Me with Ph increases the ICT energies. Cyclic voltammetric studies show irreversible reduction processes, together with oxidation waves that are irreversible for R = Me, but reversible for R = Ph. Single crystal X-ray structures have been determined for three of the methyl ester-substituted stilbazolium salts and for the Cl⁻ salts of their picolinium precursors. Time-dependent density functional theory calculations afford reasonable predictions of ICT energies, but greater rigour is necessary for –NPh₂ derivatives. The four new acid-functionalized dyes give moderate sensitization efficiencies (ca. 0.2 % ) when using TiO₂-based photoanodes, with relatively higher values for R = Ph vs Me, while larger efficiencies (up to 0.8 % ) are achieved with ZnO substrates.