Enhanced Light‐Harvesting Capability of a Panchromatic Ru(II) Sensitizer Based on π‐Extended Terpyridine with a 4‐Methylstylryl Group for Dye‐Sensitized Solar Cells |
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Authors: | Youhei Numata Surya Prakash Singh Ashraful Islam Munetaka Iwamura Atsushi Imai Koichi Nozaki Liyuan Han |
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Affiliation: | 1. Photovoltaic Materials Unit, National Institute for Materials Science, Sengen 1‐2‐1, Tsukuba, Ibaraki, 305‐0047, Japan;2. Inorganic and Physical Chemistry Division, CSIR‐Indian Institute of Chemical Technology, Uppal Road, Tarnaka, Hyderabad, 500607, India;3. Department of Chemistry, Graduate School of Science and Engineering, University of Toyama, Gohuku 3190, Toyama‐shi, Toyama, 930‐8555, Japan;4. State Key Laboratory of Metal Matrix Composites, Shanghai Jiaotong University, Shanghai 200240, China |
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Abstract: | A novel Ru π‐expanded terpyridyl sensitizer, referred to as HIS‐2, is prepared based on the molecular design strategy of substitution with a moderately electron‐donating 4‐methylstyryl group onto the terpyridyl ligand. The HIS‐2 dye exhibits a slightly increased metal‐to‐ligand charge transfer (MLCT) absorption at around 600 nm and an intense π–π* absorption in the UV region compared with a black dye. Density functional theory calculations reveal that the lowest unoccupied molecular orbital (LUMO) is distributed over the terpyridine and 4‐methylstyryl moieties, which enhances the light‐harvesting capability and is appropriate for smooth electron injection from the dye to the TiO2 conduction band. The incident photon‐to‐electricity conversion efficiency spectrum of HIS‐2 exhibits better photoresponse compared with black dye over the whole spectral region as a result of the extended π‐conjugation. A DSC device based on black dye gives a short‐circuit current (JSC) of 21.28 mA cm?2, open‐circuit voltage (VOC) of 0.69 V, and fill factor (FF) of 0.72, in an overall conversion efficiency (η) of 10.5%. In contrast, an HIS‐2 based cell gives a higher JSC value of 23.07 mA cm?2 with VOC of 0.68 V, and FF of 0.71, and owing to the higher JSC value of HIS‐2, an improved η value of 11.1% is achieved. |
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Keywords: | dye‐sensitized solar cells structure‐property relationship Ru sensitizer mesoporous TiO2 film |
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