Synthesis and Characterization of 5-Hexyl Benzothiadiazole

Yu, Young Moon; Hu, Zhi Chao; Wang, Xiao Jia; Lv, Hai Jun; Liu, Lei; Chen, Ai Bing; Fang, Jing; Yang, Xiu‐Wei

doi:10.4028/www.scientific.net/amr.1070-1072.630

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“…THF was dried over 4 Å molecular sieves and distilled under nitrogen from sodium benzophenone prior to use. Tetrabutylammonium hexafluorophosphate (TBAPF 6 ) was vacuum-dried for 48 h. The synthesis of 1a is described in the SI, and 1b and 1c were synthesized according to the reported methods. , The transparent FTO conducting glass (fluorine-doped SnO 2 ; transmission >90% in the visible range; sheet resistance 15 Ω/square) and the TiO 2 paste was purchased from Geao Science and Educational Co., Ltd. The FTO conducting glass was washed with a detergent solution, deionized water, ethanol, and acetone successively under ultrasonication for 20 min prior to use.…”

Section: Methodsmentioning

confidence: 99%

Efficient Solar Cells Based on Porphyrin Dyes with Flexible Chains Attached to the Auxiliary Benzothiadiazole Acceptor: Suppression of Dye Aggregation and the Effect of Distortion

Yang

Tang

et al. 2017

ACS Appl. Mater. Interfaces

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Donor-π-acceptor-type porphyrin dyes have been widely used for the fabrication of efficient dye-sensitized solar cells (DSSCs) owing to their strong absorption in the visible region and the ease of modifying their chemical structures and photovoltaic behavior. On the basis of our previously reported efficient porphyrin dye XW11, which contains a phenothiazine-based electron donor, a π-extending ethynylene unit, and an auxiliary benzothiadiazole acceptor, we herein report the syntheses of novel porphyrin dyes XW26-XW28 by introducing one or two alkyl/alkoxy chains into the auxiliary acceptor. The introduced chains can effectively suppress dye aggregation. As a result, XW26-XW28 show excellent photovoltages of 700, 701, and 711 mV, respectively, obviously higher than 645 mV obtained for XW11. Nevertheless, the optimized structures of XW26 and XW27 exhibit severe distortion, showing large dihedral angles of 57.2° and 44.0°, respectively, between the benzothiadiazole and benzoic acid units, resulting from the steric hindrance between the benzoic acid unit and the neighboring alkyl/alkoxy chain on the benzothiadiazole unit, and thus blue-shifted absorption, decreased photocurrents. and low efficiencies of 5.19% and 6.42% were observed for XW26 and XW27, respectively. Interestingly, XW26 exhibits a more blue-shifted absorption spectrum relative to XW27, indicating that the steric hindrance of the alkyl/alkoxy chains has a more pronounced effect than the electronic effect. Different from XW26 and XW27, XW28 contains only one alkyl chain neighboring the ethynylene unit, which does not induce obvious steric hindrance with the benzoic acid unit, and thus distortion of the molecule is not seriously aggravated compared with XW11. Hence, its absorption spectrum and photocurrent are similar to those of XW11. As a result, a higher efficiency of 9.12% was achieved for XW28 because of its suppressed dye aggregation and higher photovoltage. It is worth noting that a high efficiency of 10.14% was successfully achieved for XW28 upon coadsorption with CDCA, which is also higher than the corresponding efficiency obtained for XW11. These results provide a novel approach for developing efficient porphyrin dyes by introducing chains into the suitable position of the auxiliary benzothiadiazolyl moiety to suppress dye aggregation, without seriously aggravating distortion of the dye molecules.

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Section: Methodsmentioning

confidence: 99%