摘要/Abstract

设计合成了三种含苯并噻二唑的吩噻嗪类有机染料光敏剂JY50~JY52，在对其光物理和电化学性质进行研究的基础上，使用三种染料对纳米TiO₂电极进行敏化制备太阳能电池器件，并系统研究了其光电转化效率及电荷传输阻抗等光伏特性.研究结果表明，在染料分子中引入共轭基团有助于其摩尔吸光系数的提升，从而提升光电流.两个长烷基链的引入能够有效地抑制染料分子激发态电子在TiO₂光阳极表面的电子复合，从而提升其电子注入效率.其中，在AM 1.5（100 mW·cm^-2）的模拟光强下，基于碘电解质的染料JY51电池器件获得了7.61%的光电转化效率.
关键词: 吩噻嗪, 苯并噻二唑, 有机染料, 染料敏化太阳能电池, 光电转化效率
Dye-sensitized solar cells (DSSCs), as an emerging solar energy conversion technology, have attracted increasing attention for their ease of fabrication, low production cost, wide variety of dye structure, and high power conversion efficiency (PCE). As the critical component of DSSCs, photosensitizers play an important role in photon capturing, charge generation and separation, as well as electron injection at the semiconductor interface. Efforts on the design and synthesis of photosensitizers are thus an effective and straightforward way to tune the photovoltaic performance. In this article, three novel phenothiazine-based D-A-π-A type organic dyes (JY50~JY52) featuring benzothiadiazole units as auxiliary acceptors have been synthesized and applied in DSSCs. The introduction of auxiliary acceptor would take the advantages of the optimization of the dyes' energy levels and light absorption. To get more impressive device efficiency, 4-hexylbenzene group was decorated onto phenothiazine donor and has proved to be effective for improving the molar absorption coefficient and suppressing the charge recombination, finally resulting in the enhancement of photocurrent (J_sc) and photovoltage (Voc). In order to investigate the effect of different electron acceptor/anchoring group, benzoic acid and cyanoacrylic acid, which are widely applied in porphyrin-based dyes and metal-free organic dyes, respectively, are employed here to construct the target dyes. As we can see from the obtained photovoltaic performance data, dyes (JY50 and JY51) with benzoic acid anchor seem more beneficial to gain a higher Voc, this may be ascribed to its nearly vertical adsorption geometry on the TiO₂ interface and the resulting decrease of the charge recombination. As for dye (JY52) with cyanoacrylic acid anchor, a better J_sc value is achieved because cyanoacrylic acid endows dye an extended conjugated system and an enhanced intramolecular charge transfer. Under AM 1.5 solar light conditions, the dye JY51 with 4-hexylbenzene unit and benzoic acid acceptor exhibited the highest PCE of 7.61%, with Voc of 797 mV and J_sc of 14.21 mA·cm^-2.
Key words: phenothiazine, benzothiadiazole, organic dye, dye-sensitized solar cell, power conversion efficiency


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