Novel Ruthenium Sensitizers with a Phenothiazine Conjugated Bipyridyl Ligand for High-Efficiency Dye-Sensitized Solar Cells

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• 作者：Zhijie She ; Yangyang Cheng ; Luoqiang Zhang ; Xiaoyu Li ; Di Wu ; Qiang Guo ; Jingbo Lan ; Ruilin Wang ; Jingsong You
• 刊名：ACS Applied Materials & Interfaces
• 出版年：2015
• 出版时间：December 23, 2015
• 年：2015
• 卷：7
• 期：50
• 页码：27831-27837
• 全文大小：399K
• ISSN：1944-8252

文摘

Two efficient ruthenium sensitizers with a phenothiazine-modified bipyridine as an ancillary ligand, coded SCZ-1 and SCZ-2, have been developed as dyes in dye-sensitized solar cells (DSSCs). Both sensitizers exhibit low-energy metal-to-ligand charge transfer (MLCT) bands centered at 539 nm with high molar extinction coefficients of 1.77 × 10⁴ M^–1 cm^–1 for SCZ-1 and 1.66 × 10⁴ M^–1 cm^–1 for SCZ-2, which are significantly higher than the corresponding value for the reference N719 (1.27 × 10⁴ M^–1 cm^–1), indicating that the light-harvesting capacity of ruthenium sensitizers can be reinforced by introducing phenothiazine moieties into the bipyridine ligand. Under AM 1.5G irradiation (100 mW cm^–2), SCZ-1 and SCZ-2 sensitized DSSC devices show impressive power conversion efficiencies (PCE) up to 10.4% by using of iodide-based electrolytes, which exceeds that of N719 (9.9%) under the same conditions. Both of the open circuit voltage (V_OC) and fill factor (FF) of SCZ-sensitized solar cells approximate to those of N719-sensitized cell. The relatively higher efficiencies of the SCZ-sensitized cells than that of N719-sensitized cell come from their higher short-circuit photocurrent density (J_SC), which may be mainly attributed to the high absorption coefficient. The absorption spectrum and device efficiency of SCZ-1 are both quite close to those of SCZ-2, suggesting that the difference in alkyl chains on the N atom of phenothiazine is not a decisive factor in affecting the photovoltaic performance of dyes.