Physical and Materials Chemistry Division, CSIR-National Chemical Laboratory, CSIR-Network of Institutes for Solar Energy , Dr. Homi Bhabha Road, Pune 411008, India.
Academy of Scientific and Innovative Research (AcSIR) , New Delhi 110025, India.
ACS Appl Mater Interfaces. 2017 Sep 27;9(38):32698-32712. doi: 10.1021/acsami.7b08346. Epub 2017 Sep 12.
Far-red-absorbing squaraines possessing high molar absorptivity (>10 M cm) are being attracted as high-efficiency chromophores in dye-sensitized solar cells (DSSCs). A series of donor-acceptor-donor-π spacer-acceptor (D-A-D-π-A) unsymmetrical squaraines, PSQ1-5, with indoline donor and squaric/cyanoacetic acid acceptor units, were designed for sensitized solar cells. For extending the absorption toward the near-infrared region (NIR) and controlling the orientation on the TiO surface, benzene (PSQ1 and PSQ2) and thiophene (PSQ3-5) π-spacers and out-of-plane branched alkyl groups at the indoline that are away (PSQ1, PSQ3, and PSQ5) or near (PSQ2 and PSQ4) the anchoring group, respectively, were introduced. Dynamic aggregation tendency of PSQ1 and PSQ3 than that of their isomers systematically modulates the orientation on the TiO surface, which in turn enhances photovoltaic performance. Absorptance on a thin transparent TiO film shows a visible-to-NIR response with an onset around 800 nm for PSQ3-5. Although there is close resemblance in electrochemical redox levels, their high injection efficiency and recombination resistance differentiated their impact on the way of anchoring and the dihedral angle between D-A-D units and π-spacers. DSSCs sensitized with PSQ5 achieved a PCE of 8.15% under simulated AM 1.5G illumination (100 mW cm), with the current density (J) and open-circuit voltage (V) of 19.73 mA cm and 630 mV, respectively. A clear comparison of the incident-photon-to-current conversion efficiency versus the light-harvesting efficiency correlates the structure-property relationship with J obtained for PSQ dyes. Electrochemical impedance spectroscopy was carried out to examine the TiO/dye/electrolyte interface for further confirmation of the enhanced PCE of top-sp-alkylated PSQ5 over that of other dyes.
具有高摩尔吸光率（>10 M cm）的远红吸收方酸菁作为高效发色团，在染料敏化太阳能电池（DSSC）中受到关注。一系列具有吲哚供体和方酸/氰基乙酸受体单元的给体-受体-给体-π间隔基-受体（D-A-D-π-A）不对称方酸菁 PSQ1-5 被设计用于敏化太阳能电池。为了将吸收扩展到近红外区域（NIR）并控制在 TiO 表面的取向，苯（PSQ1 和 PSQ2）和噻吩（PSQ3-5）π-间隔基和吲哚上的非共面支化烷基基团分别远离（PSQ1、PSQ3 和 PSQ5）或靠近（PSQ2 和 PSQ4）锚定基团。PSQ1 和 PSQ3 的动态聚集趋势比其异构体系统地调节 TiO 表面的取向，从而增强光电性能。PSQ3-5 在薄透明 TiO 薄膜上的吸光度表现出可见至近红外响应，起始波长约为 800nm。尽管电化学氧化还原水平非常相似，但它们的高注入效率和重组电阻差异影响了它们的锚固方式和 D-A-D 单元与π-间隔基之间的二面角。用 PSQ5 敏化的 DSSC 在模拟 AM 1.5G 照明（100 mW cm）下实现了 8.15%的 PCE，电流密度（J）和开路电压（V）分别为 19.73 mA cm 和 630 mV。入射光子-电流转换效率与光捕获效率的清晰比较将结构-性能关系与 PSQ 染料的 J 相关联。进行了电化学阻抗谱研究，以检查 TiO2/染料/电解质界面，进一步确认顶部-sp-烷基化 PSQ5 的 PCE 高于其他染料。
