Dye-Sensitized Solar Cells Based On Donor-Acceptor π-Conjugated Fluorescent Dyes with a Pyridine Ring as an Electron-Withdrawing Anchoring Group
Dye-Sensitized Solar Cells Based On Donor-Acceptor π-Conjugated Fluorescent Dyes with a Pyridine Ring as an Electron-Withdrawing Anchoring Group
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DOI：
10.1002/anie.201102552
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发表时间：
2011-01-01
影响因子：
16.6
通讯作者：
Harima, Yutaka
中科院分区：
文献类型：
--
作者：
Ooyama, Yousuke;Inoue, Shogo;Harima, Yutaka
自1991年Grätzel及其同事首次报道染料敏化太阳能电池（DSSC）以来，DSSC因其高入射太阳能转换效率和低生产成本而受到相当大的关注。最近，为了提高能量转换效率，许多研究集中在开发新的无金属有机染料敏化剂上。[2-9]特别是，具有供电子（D）和受电子（A）基团通过π-共轭桥连接的给体-受体π-共轭（D-π-A）染料，具有广泛而强烈的吸收，被认为是最有前途的有机染料之一。增感剂。d-π-A染料的光谱特征与从染料的供体到受体部分的分子内电荷转移（ICT）激发相关联，从而导致从激发的染料通过受体部分到TiO 2的导带（CB）中的有效电子转移。大多数D-π-A染料，如香豆素、多烯、噻吩和二氢吲哚，具有作为电子供体的二烷基胺或二苯胺部分，以及作为电子受体以及用于连接到TiO 2表面的锚定基团的羧酸、氰基丙烯酸或罗丹宁-3-乙酸部分。[2-9]羧基通过与TiO 2表面形成强酯键，使染料和TiO 2之间能够进行良好的电子通信。然而，只要羧基用作锚和电子受体，用于DSSC的新d-π-A染料的开发就受到限制。为了创造新的和有效的用于DSSC的d-π-A染料，需要新的分子设计，例如敏化剂的电子接受部分与TiO 2表面之间形成强相互作用。在此，我们提出使用吡啶环作为吸电子和锚定基团代替常规羧基。我们已经证明，新开发的具有吡啶环的d-π-A荧光染料NI 3 -6可以通过吡啶的氮原子上的孤对电子与TiO 2的刘易斯酸中心之间的强配位键合吸附到TiO 2表面上，从而获得与其中吡啶环被羧基苯基取代的NI 1和NI 2相当或更高的电子注入效率（方案1;详细的合成步骤见支持信息）。NI 1 -6在1，4-二氧六环中的吸收光谱和荧光光谱如图1所示，其光谱数据如下：
Since the first report of dye-sensitized solar cells (DSSCs) by Grätzel and co-workers in 1991,[1] DSSCs have received considerable attention because of their high incident solar light to electricity conversion efficiency and low cost of production. Recently, in order to increase power conversion efficiency, much research has focused on the development of new metal-free organic dye sensitizers.[2–9] In particular, donor–acceptor π-conjugated (D-π-A) dyes with both the electron-donating (D) and electron-accepting (A) groups linked by a π-conjugated bridge that exhibits broad and intense absorption, are proposed as one of the most promising organic dye sensitizers. The spectral features of the d-π-A dyes are associated with the intramolecular charge transfer (ICT) excitation from the donor to the acceptor moiety of the dye, thus leading to efficient electron transfer from the excited dye through the acceptor moiety into the conduction band (CB) of TiO2. Most of the D-π-A dyes, such as coumarins, polyenes, thiophenes, and indolines, have dialkylamine or diphenylamine moieties as electron donor, and carboxylic acid, cyanoacrylic acid, or rhodanine-3-acetic acid moieties that act as electron acceptors as well as anchoring groups for attachment to a TiO2 surface.[2–9] The carboxyl group enables good electronic communication between the dye and TiO2 by forming a strong ester linkage with the TiO2 surface. However, development of new d-π-A dyes for DSSCs is limited as long as the carboxyl group is employed as an anchor and electron acceptor. To create new and efficient d-π-A dyes for DSSCs, an new molecular design such as formation of a strong interaction between the electronaccepting moiety of sensitizers and TiO2 surface is required. Herein, we propose the use of a pyridine ring as an electron-withdrawing and anchoring group in place of a conventional carboxy group. We have demonstrated that the newly developed d-π-A fluorescent dyes NI3–6 with a pyridine ring can adsorb onto a TiO2 surface by strong coordinate bonding between the lone pair of electrons on the nitrogen atom of the pyridine, and the Lewis acid sites of TiO2 to give electron injection efficiencies comparable to or higher than those for NI1 and NI2 where the pyridine ring is replaced with carboxyphenyl group (Scheme1; see the Supporting Information for the detailed synthetic procedures). The absorption and fluorescence spectra of NI1–6 in 1, 4-dioxane are shown in Figure 1 and their spectral data are