A symmetrical squaraine dye altered to possess dicyanovinylene functionality on a carbonyl group of the cyclobutene core (SQM1a) was synthesized to elucidate the effects of the conformationally locked-in cis-like form ensured by the steric repulsion of dicyanovinylenes on the performance of dye-sensitized solar cells (DSSCs) through a comparison with an unsymmetrical analogue bearing one carboxy group (SQM1b) and a standard squaraine dye (MSQ). The FT-IR spectrum of the TiO2 thin film immersed in the dye solution suggested that the linkages between the dye and TiO2 were formed by both carboxy groups symmetrically incorporated on the π-conjugation of dyes. The symmetrical and conformationally locked structure of SQM1a brought about a decrease in the non-radiative decay rate, which may have been induced by suppression of the possible photoisomerization of squaraines. In accordance with the finding of non-radiative decay, a DSSC fabricated with SQM1a exhibited a significantly enhanced short-circuit current density, which revealed an efficient electron injection derived from the double-anchored and conformationally locked structure of SQM1a. Consequently, the performance of DSSCs fabricated with SQM1a was higher than the performance of those fabricated with SQM1b and MSQ. This indicates that substantial advantages can be derived by restricting the conformation of symmetrical squaraine dyes.
一种具有对称结构的方形花菁
染料,其在
环丁烯核心的羰基上具有二
氰乙烯基功能团(SQM1a),通过与具有一个羧基的不对称类似物(SQM1b)和标准方形花菁
染料(MSQ)的比较,合成了该
染料,以阐明由二
氰乙烯基的立体排斥确保的构象锁定顺式形式对
染料敏化太阳能电池(DSSCs)性能的影响。TiO2薄膜沉浸在
染料溶液中的FT-IR光谱表明,
染料与TiO2之间的键合是由对称地结合在
染料π共轭体系上的两个羧基形成的。SQM1a的对称和构象锁定结构导致非辐射衰减速率的降低,这可能是由抑制方形花菁的可能光异构化引起的。与非辐射衰减的发现一致,采用SQM1a制备的DSSC表现出显著增强的短路电流密度,这揭示了源自SQM1a的双锚定和构象锁定结构的有效的电子注入。因此,采用SQM1a制备的DSSCs的性能高于采用SQM1b和MSQ制备的那些。这表明,通过限制对称方形花菁
染料的构象,可以获得实质性的优势。