Substitution of Carbazole Modified Fluorenes asπ-Extension in Ru(II) Complex-Influence on Performance of Dye-Sensitized Solar Cells

[摘要] A new high molar extinction coefficient ruthenium(II) bipyridyl complex “cis-Ru(4,4′-bis(9,9-dibutyl-7-(3,6-di-tert-butyl-9H-carbazol-9-yl)-9H-fluoren-2-yl)-2,2′-bipyridine)(2,2′-bipyridine-4,4′-dicarboxylic acid)(NCS)2,BPFC” has been synthesized and characterized by FT-IR,1H-NMR, and ESI-MASS spectroscopes. The sensitizer showed molar extinction coefficient of18.5×103 M−1cm−1, larger as compared to the referenceN719, which showed14.4×103 M−1cm−1. The test cells fabricated usingBPFCsensitizer employing high performance volatile electrolyte, (E01) containing 0.05 M I2, 0.1 M LiI, 0.6 M 1,2-dimethyl-3-n-propylimidazolium iodide, 0.5 M 4-tert-butylpyridine in acetonitrile solvent, exhibited solar-to-electric energy conversion efficiency (η) of 4.65% (short-circuit current density (JSC) = 11.52 mA/cm2, open-circuit voltage (VOC) = 566 mV, fill factor = 0.72) under Air Mass 1.5 sunlight, lower as compared to the referenceN719 sensitized solar cell, fabricated under similar conditions, which exhibitedη-value of 6.5% (JSC= 14.3 mA/cm2,VOC= 640 mV, fill factor = 0.71). UV-Vis measurements conducted on TiO2films showed decreased film absorption ratios forBPFCas compared to those of referenceN719. Staining TiO2electrodes immediately after sonication of dye solutions enhanced film absorption ratios ofBPFCrelative to those ofN719. Time-dependent density functional theory (TD-DFT) calculations show higher oscillation strengths for 4,4′-bis(9,9-dibutyl-7-(3,6-di-tert-butyl-9H-carbazol-9-yl)-9H-fluoren-2-yl)-2,2′-bipyridine relative to 2,2′-bipyridine-4,4′-dicarboxylic acid and increased spectral response for the correspondingBPFCcomplex.

[学科分类] 电子、光学、磁材料